SECURITIES AND EXCHANGE COMMISSION
                              WASHINGTON, D.C. 20549

                                  SCHEDULE 13D
                    UNDER THE SECURITIES EXCHANGE ACT OF 1934
                                (Amendment No. 3)

                         MAGELLAN HEALTH SERVICES, INC.
                                (Name of Issuer)

                             ORDINARY COMMON SHARES
                         (Title of Class of Securities)

                               CUSIP No. 559079207
                                 (CUSIP Number)

                                ONEX CORPORATION
                               CANADA TRUST TOWER
                           161 BAY STREET - 49TH FLOOR
                         TORONTO, CANADA M5J 2S1 CANADA
                          ATTENTION: EWOUT R. HEERSINK
                                 (416) 362-7711

                                   COPIES TO:

                             JOEL I. GREENBERG, ESQ.
                                KAYE SCHOLER LLP
                                 425 PARK AVENUE
                            NEW YORK, NEW YORK 10022
                                 (212) 836-8000

                                  JUNE 7, 2005

If the filing person has previously filed a statement on Schedule 13G to report
the acquisition which is the subject of this Schedule 13D, and is filing this
schedule because of Rule 13d-1(b)(3) or (4), check the following box [ ].

Note: Six copies of this statement, including all exhibits, should be filed with
the Commission. See Rule 13d-1(a) for other parties to whom copies are to be
sent.

*The remainder of this cover page shall be filled out for a reporting person's
initial filing on this form with respect to the subject class of securities, and
for any subsequent amendment containing information which would alter
disclosures provided in a prior cover page.

The information required on the remainder of this cover page shall not be deemed
to be "filed" for the purpose of Section 18 of the Securities Exchange Act of
1934 ("Act") or otherwise subject to the liabilities of that section of the Act
but shall be subject to all other provisions of the Act (however, see the
Notes).



                                  SCHEDULE 13D

CUSIP NO. 559079207                                           PAGE 2 OF 12 PAGES

1.                NAME OF REPORTING PERSON
                  S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

                  Magellan Holdings LP
--------------------------------------------------------------------------------
2.                CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*      (a)[ ]
                                                                         (b)[ ]
--------------------------------------------------------------------------------
3.                SEC USE ONLY
--------------------------------------------------------------------------------
4.                SOURCE OF FUNDS*

                  WC
--------------------------------------------------------------------------------
5.                CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
                  PURSUANT TO ITEMS 2(d) or 2(e)                             [ ]
--------------------------------------------------------------------------------
6.                CITIZENSHIP OR PLACE OF ORGANIZATION

                  Delaware
--------------------------------------------------------------------------------
              7.  SOLE VOTING POWER
 NUMBER OF        -0-
  SHARES      ------------------------------------------------------------------
BENEFICIALLY  8.  SHARED VOTING POWER
 OWNED BY         3,762,713 shares of Ordinary Common Stock issuable upon
  EACH            conversion of shares of Multiple and Variable Vote Restricted
 REPORTING        Convertible Common Stock ("MV Common Stock") of the Issuer.
  PERSON      ------------------------------------------------------------------
   WITH       9.  SOLE DISPOSITIVE POWER
                  -0-
              ------------------------------------------------------------------
              10. SHARED DISPOSITIVE POWER
                  3,762,713 shares of Ordinary Common Stock issuable upon
                  conversion of shares of MV Common Stock of the Issuer.
--------------------------------------------------------------------------------
11.               AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING
                  PERSON
                  3,762,713 shares of Ordinary Common Stock issuable upon
                  conversion of shares of MV Common Stock of the Issuer.
--------------------------------------------------------------------------------
12.               CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
                  SHARES*                                                    [ ]
--------------------------------------------------------------------------------
13.               PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                  10.6% of the Issuer's shares of Ordinary Common Stock,
                  assuming conversion of all of the Reporting Person's shares of
                  MV Common Stock into Ordinary Common Stock and conversion of
                  4,209,000 shares of MV Common Stock into Ordinary Common Stock
                  and subsequent sale thereof by the Reporting Persons on May
                  20, 2005, pursuant to an underwritten offering and conversion
                  of 537,500 shares of MV Common Stock into Ordinary Common
                  Stock and subsequent sale thereof by the Reporting Person on
                  June 7, 2005, pursuant to an underwritten offering (assuming
                  26,936,530 shares of Ordinary Common Stock outstanding prior
                  to the offerings).
--------------------------------------------------------------------------------
14.               TYPE OF REPORTING PERSON*

                  PN
--------------------------------------------------------------------------------

                      *SEE INSTRUCTIONS BEFORE FILLING OUT
          INCLUDE BOTH SIDES OF THE COVER PAGE, RESPONSES TO ITEMS 1-7
      (INCLUDING EXHIBITS) OF THE SCHEDULE, AND THE SIGNATURE ATTESTATION.

                               Page 2 of 12 Pages



                                  SCHEDULE 13D

CUSIP NO. 559079207                                           PAGE 3 OF 12 PAGES

1.                NAME OF REPORTING PERSON
                  S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

                  Onex Partners LP
--------------------------------------------------------------------------------
2.                CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*      (a)[ ]
                                                                         (b)[ ]
--------------------------------------------------------------------------------
3.                SEC USE ONLY
--------------------------------------------------------------------------------
4.                SOURCE OF FUNDS*

                  AF
--------------------------------------------------------------------------------
5.                CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
                  PURSUANT TO ITEMS 2(d) or 2(e)                             [ ]
--------------------------------------------------------------------------------
6.                CITIZENSHIP OR PLACE OF ORGANIZATION

                  Delaware
--------------------------------------------------------------------------------
              7.  SOLE VOTING POWER
                  -0-
 NUMBER OF    ------------------------------------------------------------------
  SHARES      8.  SHARED VOTING POWER
BENEFICIALLY      3,762,713 shares of Ordinary Common Stock issuable upon
  OWNED BY        conversion of shares of MV Common Stock of the Issuer.
   EACH       ------------------------------------------------------------------
 REPORTING    9.  SOLE DISPOSITIVE POWER
  PERSON          -0-
   WITH       ------------------------------------------------------------------
              10. SHARED DISPOSITIVE POWER
                  3,762,713 shares of Ordinary Common Stock issuable upon
                  conversion of shares of MV Common Stock of the Issuer.
--------------------------------------------------------------------------------
11.               AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                  3,762,713 shares of Ordinary Common Stock issuable upon
                  conversion of shares of MV Common Stock of the Issuer.
--------------------------------------------------------------------------------
12.               CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
                  SHARES*                                                    [ ]
--------------------------------------------------------------------------------
13.               PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                  10.6% of the Issuer's shares of Ordinary Common Stock,
                  assuming conversion of all of the Reporting Person's shares of
                  MV Common Stock into Ordinary Common Stock and conversion of
                  4,209,000 shares of MV Common Stock into Ordinary Common Stock
                  and subsequent sale thereof by the Reporting Persons on May
                  20, 2005, pursuant to an underwritten offering and conversion
                  of 537,500 shares of MV Common Stock into Ordinary Common
                  Stock and subsequent sale thereof by the Reporting Person on
                  June 7, 2005, pursuant to an underwritten offering (assuming
                  26,936,530 shares of Ordinary Common Stock outstanding prior
                  to the offerings).
--------------------------------------------------------------------------------
14.               TYPE OF REPORTING PERSON*

                  PN
--------------------------------------------------------------------------------

                      *SEE INSTRUCTIONS BEFORE FILLING OUT
          INCLUDE BOTH SIDES OF THE COVER PAGE, RESPONSES TO ITEMS 1-7
      (INCLUDING EXHIBITS) OF THE SCHEDULE, AND THE SIGNATURE ATTESTATION.

                               Page 3 of 12 Pages



                                  SCHEDULE 13D

CUSIP NO. 559079207                                           PAGE 4 OF 12 PAGES

1.                NAME OF REPORTING PERSON
                  S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

                  Onex Partners GP LP
--------------------------------------------------------------------------------
2.                CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a)[ ]
                                                                          (b)[ ]
--------------------------------------------------------------------------------
3.                SEC USE ONLY
--------------------------------------------------------------------------------
4.                SOURCE OF FUNDS*

                  AF
--------------------------------------------------------------------------------
5.                CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
                  PURSUANT TO ITEMS 2(d) or 2(e)                             [ ]
--------------------------------------------------------------------------------
6.                CITIZENSHIP OR PLACE OF ORGANIZATION

                  Delaware
--------------------------------------------------------------------------------
              7.  SOLE VOTING POWER
                  -0-
              ------------------------------------------------------------------
 NUMBER OF    8.  SHARED VOTING POWER
  SHARES          3,762,713 shares of Ordinary Common Stock issuable upon
BENEFICIALLY      conversion of shares of MV Common Stock of the Issuer.
  OWNED BY    ------------------------------------------------------------------
   EACH       9.  SOLE DISPOSITIVE POWER
 REPORTING        -0-
  PERSON      ------------------------------------------------------------------
   WITH       10. SHARED DISPOSITIVE POWER
                  3,762,713 shares of Ordinary Common Stock issuable upon
                  conversion of shares of MV Common Stock of the Issuer.
--------------------------------------------------------------------------------
11.               AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                  3,762,713 shares of Ordinary Common Stock issuable upon
                  conversion of shares of MV Common Stock of the Issuer.
--------------------------------------------------------------------------------
12.               CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
                  SHARES*                                                    [ ]
--------------------------------------------------------------------------------
13.               PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                  10.6% of the Issuer's shares of Ordinary Common Stock,
                  assuming conversion of all of the Reporting Person's shares of
                  MV Common Stock into Ordinary Common Stock and conversion of
                  4,209,000 shares of MV Common Stock into Ordinary Common Stock
                  and subsequent sale thereof by the Reporting Persons on May
                  20, 2005, pursuant to an underwritten offering and conversion
                  of 537,500 shares of MV Common Stock into Ordinary Common
                  Stock and subsequent sale thereof by the Reporting Person on
                  June 7, 2005, pursuant to an underwritten offering (assuming
                  26,936,530 shares of Ordinary Common Stock outstanding prior
                  to the offerings).
--------------------------------------------------------------------------------
14.               TYPE OF REPORTING PERSON*

                  PN
--------------------------------------------------------------------------------

                      *SEE INSTRUCTIONS BEFORE FILLING OUT
          INCLUDE BOTH SIDES OF THE COVER PAGE, RESPONSES TO ITEMS 1-7
      (INCLUDING EXHIBITS) OF THE SCHEDULE, AND THE SIGNATURE ATTESTATION.

                               Page 4 of 12 Pages



                                  SCHEDULE 13D

CUSIP NO. 559079207                                           PAGE 5 OF 12 PAGES

1.                NAME OF REPORTING PERSON
                  S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

                  Onex Partners GP Inc.
--------------------------------------------------------------------------------
2.                CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a)[ ]
                                                                          (b)[ ]
--------------------------------------------------------------------------------
3.                SEC USE ONLY
--------------------------------------------------------------------------------
4.                SOURCE OF FUNDS*

                  AF
--------------------------------------------------------------------------------
5.                CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
                  PURSUANT TO ITEMS 2(d) or 2(e)                             [ ]
--------------------------------------------------------------------------------
6.                CITIZENSHIP OR PLACE OF ORGANIZATION

                  Delaware
--------------------------------------------------------------------------------
              7.  SOLE VOTING POWER
                  -0-
              ------------------------------------------------------------------
 NUMBER OF    8.  SHARED VOTING POWER
   SHARES         3,762,713 shares of Ordinary Common Stock issuable upon
BENEFICIALLY      conversion of shares of MV Common  Stock of the Issuer.
   OWNED      ------------------------------------------------------------------
  BY EACH     9.  SOLE DISPOSITIVE POWER
 REPORTING        -0-
PERSON WITH   ------------------------------------------------------------------
              10. SHARED DISPOSITIVE POWER
                  3,762,713 shares of Ordinary Common Stock issuable upon
                  conversion of shares of MV Common Stock of the Issuer.
--------------------------------------------------------------------------------
11.               AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                  3,762,713 shares of Ordinary Common Stock issuable upon
                  conversion of shares of MV Common Stock of the Issuer.
--------------------------------------------------------------------------------
12.               CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
                  SHARES*                                                    [ ]
--------------------------------------------------------------------------------
13.               PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                  10.6% of the Issuer's shares of Ordinary Common Stock,
                  assuming conversion of all of the Reporting Person's shares of
                  MV Common Stock into Ordinary Common Stock and conversion of
                  4,209,000 shares of MV Common Stock into Ordinary Common Stock
                  and subsequent sale thereof by the Reporting Persons on May
                  20, 2005, pursuant to an underwritten offering and conversion
                  of 537,500 shares of MV Common Stock into Ordinary Common
                  Stock and subsequent sale thereof by the Reporting Person on
                  June 7, 2005, pursuant to an underwritten offering (assuming
                  26,936,530 shares of Ordinary Common Stock outstanding prior
                  to the offerings).
--------------------------------------------------------------------------------
14.               TYPE OF REPORTING PERSON*

                  CO
--------------------------------------------------------------------------------

                      *SEE INSTRUCTIONS BEFORE FILLING OUT
          INCLUDE BOTH SIDES OF THE COVER PAGE, RESPONSES TO ITEMS 1-7
      (INCLUDING EXHIBITS) OF THE SCHEDULE, AND THE SIGNATURE ATTESTATION.

                               Page 5 of 12 Pages



                                  SCHEDULE 13D
CUSIP NO. 559079207                                           PAGE 6 OF 12 PAGES

1                 NAME OF REPORTING PERSON
                  S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

                  Onex Corporation
--------------------------------------------------------------------------------
2                 CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a)[ ]
                                                                          (b)[ ]
--------------------------------------------------------------------------------
3                 SEC USE ONLY
--------------------------------------------------------------------------------
4                 SOURCE OF FUNDS*

                  AF
--------------------------------------------------------------------------------
5                 CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
                  PURSUANT TO ITEMS 2(d) or 2(e)                             [ ]
--------------------------------------------------------------------------------
6                 CITIZENSHIP OR PLACE OF ORGANIZATION

                  Ontario, Canada
--------------------------------------------------------------------------------
              7   SOLE VOTING POWER
                  -0-
              ------------------------------------------------------------------
 NUMBER OF    8   SHARED VOTING POWER
   SHARES         3,762,713 shares of Ordinary Common Stock issuable upon
BENEFICIALLY      conversion of shares of MV Common Stock of the Issuer.
  OWNED BY    ------------------------------------------------------------------
    EACH      9   SOLE DISPOSITIVE POWER
 REPORTING        -0-
PERSON WITH   ------------------------------------------------------------------
              10  SHARED DISPOSITIVE POWER
                  3,762,713 shares of Ordinary Common Stock issuable upon
                  conversion of shares of MV Common Stock of the Issuer.
--------------------------------------------------------------------------------
11                AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                  3,762,713 shares of Ordinary Common Stock issuable upon
                  conversion of shares of MV Common Stock of the Issuer.
--------------------------------------------------------------------------------
12                CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
                  SHARES*                                                    [ ]
--------------------------------------------------------------------------------
13                PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11)
                  10.6% of the Issuer's shares of Ordinary Common Stock,
                  assuming conversion of all of the Reporting Person's shares of
                  MV Common Stock into Ordinary Common Stock and conversion of
                  4,209,000 shares of MV Common Stock into Ordinary Common Stock
                  and subsequent sale thereof by the Reporting Persons on May
                  20, 2005, pursuant to an underwritten offering and conversion
                  of 537,500 shares of MV Common Stock into Ordinary Common
                  Stock and subsequent sale thereof by the Reporting Person on
                  June 7, 2005, pursuant to an underwritten offering (assuming
                  26,936,530 shares of Ordinary Common Stock outstanding prior
                  to the offerings).
--------------------------------------------------------------------------------
14                TYPE OF REPORTING PERSON*

                  CO
--------------------------------------------------------------------------------

                      *SEE INSTRUCTIONS BEFORE FILLING OUT
          INCLUDE BOTH SIDES OF THE COVER PAGE, RESPONSES TO ITEMS 1-7
      (INCLUDING EXHIBITS) OF THE SCHEDULE, AND THE SIGNATURE ATTESTATION.

                               Page 6 of 12 Pages



                                  SCHEDULE 13D

CUSIP NO. 559079207                                           PAGE 7 OF 12 PAGES

1.                NAME OF REPORTING PERSON
                  S.S. OR I.R.S. IDENTIFICATION NO. OF ABOVE PERSON

                  Gerald W. Schwartz
--------------------------------------------------------------------------------
2.                CHECK THE APPROPRIATE BOX IF A MEMBER OF A GROUP*       (a)[ ]
                                                                          (b)[ ]
--------------------------------------------------------------------------------
3.                SEC USE ONLY
--------------------------------------------------------------------------------
4.                SOURCE OF FUNDS*

                  AF
--------------------------------------------------------------------------------
5.                CHECK BOX IF DISCLOSURE OF LEGAL PROCEEDINGS IS REQUIRED
                  PURSUANT TO ITEMS 2(d) or 2(e)                             [ ]
--------------------------------------------------------------------------------
6.                CITIZENSHIP OR PLACE OF ORGANIZATION

                  Canada
--------------------------------------------------------------------------------
              7.  SOLE VOTING POWER
                  -0-
              ------------------------------------------------------------------
 NUMBER OF    8.  SHARED VOTING POWER
  SHARES          3,762,713 shares of Ordinary Common Stock issuable upon
BENEFICIALLY      conversion of shares of MV Common Stock of the Issuer.
  OWNED BY    ------------------------------------------------------------------
   EACH       9.  SOLE DISPOSITIVE POWER
 REPORTING        -0-
  PERSON      ------------------------------------------------------------------
   WITH       10. SHARED DISPOSITIVE POWER
                  3,762,713 shares of Ordinary Common Stock issuable upon
                  conversion of shares of MV Common Stock of the Issuer.
--------------------------------------------------------------------------------
11.               AGGREGATE AMOUNT BENEFICIALLY OWNED BY EACH REPORTING PERSON
                  3,762,713 shares of Ordinary Common Stock issuable upon
                  conversion of shares of MV Common Stock of the Issuer.**
--------------------------------------------------------------------------------
12.               CHECK BOX IF THE AGGREGATE AMOUNT IN ROW (11) EXCLUDES CERTAIN
                  SHARES*                                                    [X]
--------------------------------------------------------------------------------
13.               PERCENT OF CLASS REPRESENTED BY AMOUNT IN ROW (11) 
                  10.6% of the Issuer's shares of Ordinary Common Stock,
                  assuming conversion of all of the Reporting Person's shares of
                  MV Common Stock into Ordinary Common Stock and conversion of
                  4,209,000 shares of MV Common Stock into Ordinary Common Stock
                  and subsequent sale thereof by the Reporting Persons on May
                  20, 2005, pursuant to an underwritten offering and conversion
                  of 537,500 shares of MV Common Stock into Ordinary Common
                  Stock and subsequent sale thereof by the Reporting Person on
                  June 7, 2005, pursuant to an underwritten offering (assuming
                  26,936,530 shares of Ordinary Common Stock outstanding prior
                  to the offerings).
--------------------------------------------------------------------------------
14.               TYPE OF REPORTING PERSON*

                  IN
--------------------------------------------------------------------------------

                      *SEE INSTRUCTIONS BEFORE FILLING OUT
          INCLUDE BOTH SIDES OF THE COVER PAGE, RESPONSES TO ITEMS 1-7
      (INCLUDING EXHIBITS) OF THE SCHEDULE, AND THE SIGNATURE ATTESTATION.

**    Gerald W. Schwartz expressly disclaims beneficial ownership of the shares
      of Magellan Health Services, Inc. beneficially owned by Magellan Holdings
      LP, Onex Partners LP, Onex Partners GP LP, Onex Partners GP Inc. and Onex
      Corporation.

                               Page 7 of 12 Pages



            This Amendment Number 3 (the "Third Amendment") amends and
supplements the Statement on Schedule 13D (the "Original Schedule 13D") filed on
January 16, 2004, the Amendment Number 1 to the Statement on Schedule 13D filed
on May 11, 2005 (the "First Amendment") and the Amendment Number 2 to the
Statement on Schedule 13D filed on May 27, 2005 (the "Second Amendment" together
with the Original Schedule 13D and the First Amendment, the "Schedule 13D"),
relating to the shares of Ordinary Common Stock , par value $.01 per share
("Ordinary Common Stock"), of Magellan Health Services, Inc., a Delaware
corporation (the "Issuer") previously filed by Magellan Holdings LP, a Delaware
limited partnership ("Holdings"), Onex Partners LP, a Delaware limited
partnership ("Partners"), Onex Partners GP LP, a Delaware limited partnership
("Partners GP LP"), Onex Partners GP Inc., a Delaware corporation ("Partners
GP"), Onex Corporation, an Ontario corporation ("Onex"), and Mr. Gerald W.
Schwartz ("Mr. Schwartz"). Rights to such Ordinary Common Stock were acquired
pursuant to a stock purchase agreement dated as of December 18, 2003, between
the Issuer and Holdings (the "Stock Purchase Agreement"), whereby Holdings
purchased 8,415,580 shares of Multiple and Variable Vote Restricted Convertible
Common Stock, par value $0.01 per share ("MV Common Stock") of the Issuer, which
are convertible at any time at the option of the holder into the same number of
shares of Ordinary Common stock.

            Except as specifically provided herein, this Third Amendment does
not modify any of the information previously reported on the Schedule 13D.

Item 4. Purpose of Transaction.

            Holdings has sold 537,500 MV Common Stock pursuant to an
underwritten offering as a result of the underwriter's exercise of their option
to purchase additional shares to cover over-allotments. Holdings' interest in
the Issuer's outstanding MV Common Stock has fallen below the minimum threshold
used to determine eligibility for special voting rights or privileges relating
to such MV Common Stock ownership. Accordingly, Holdings is not eligible for
special voting rights and will generally vote with Ordinary Common Stock on a
one vote per share basis.

            Pursuant to the Stock Purchase Agreement and the terms of the Third
Amended Joint Plan of Reorganization of the Issuer and certain of its
subsidiaries under Chapter 11 of the United States Bankruptcy Code dated August
18, 2003, as amended (the "Plan of Reorganization"), Holdings has an outstanding
commitment to purchase up to an additional 12,781 shares of MV Common Stock at a
price of $9.78 per share, upon settlement of disputed claims of certain of the
Issuer's creditors. In addition, Reporting Persons may from time to time acquire
shares of Ordinary Common Stock in the open market or in privately negotiated
transactions, subject to the availability of such shares at prices deemed
favorable, the Issuer's business or financial condition and to other factors and
conditions the Reporting Persons deem appropriate. In the event the Reporting
Persons acquire shares of Ordinary Common Stock, such shares will automatically
be converted into the same number of shares of MV Common Stock. See Exhibit 2.
Alternatively, the Reporting Persons may sell all or a portion of their shares
of MV Common Stock, or shares of Ordinary Common Stock obtained upon conversion
of such shares of MV Common Stock, in the open market or in privately negotiated
transactions. Holdings has registration rights with respect to the shares of
Ordinary Common Stock underlying its shares of MV Common Stock. See Exhibit 3.
Holdings has no present intention of disposing of the shares it will continue to
hold following the offering.

            Except as set forth above in the two immediately preceding
paragraphs, no Reporting Person has any present plans or proposals that relate
to or would result in: (a) the acquisition by any person of additional
securities of the Issuer, or the disposition of securities of the Issuer; (b) an
extraordinary corporate transaction, such as a merger, reorganization or
liquidation, involving the Issuer or any of its subsidiaries; (c) a sale or
transfer of a material amount of assets of the Issuer or of any of its
subsidiaries; (d) any change in the present board of directors or management of
the Issuer, including any plans or proposals to change the number or term of
such directors or to fill any existing vacancies on such board; (e) any material
change in the present capitalization or dividend policy of the Issuer; (f) any
other material change in the Issuer's business or corporate structure; (g)
changes in the Issuer's charter, by-laws or instruments corresponding thereto or
other actions that may impede the acquisition of control of the Issuer by any
person; (h) causing a class of securities of the Issuer to be delisted from a
national securities exchange or to cease to be authorized to be quoted in an
inter-dealer quotation system of a registered national securities association;
(i) a class of equity securities of the Issuer becoming eligible for termination
of registration pursuant to Section 12(g)(4) of the Securities Exchange Act of
1934; or (j) any action similar to any of those enumerated above.

                               Page 8 of 12 Pages



Item 5. Interest in Securities of the Issuer.

            (a) and (b). As of the date hereof, Holdings beneficially owns
3,762,713 shares of Ordinary Common Stock (which may be obtained at any time by
conversion of shares of MV Common Stock held by Holdings), which constitute
10.6% of the Issuer's shares of Ordinary Common Stock assuming conversion of all
of the Reporting Person's shares of MV Common Stock into Ordinary Common Stock
and conversion of 4,209,000 shares of MV Common Stock into Ordinary Common Stock
and subsequent sale thereof by the Reporting Persons on May 20, 2005, pursuant
to an underwritten offering and conversion of 537,500 shares of MV Common Stock
into Ordinary Common Stock and subsequent sale thereof by the Reporting Person
on June 7, 2005, pursuant to an underwritten offering (assuming 26,936,530
additional shares of Ordinary Common Stock outstanding prior to the offerings).

            All of the shares beneficially owned by Holdings may be deemed as
beneficially owned by each of Partners, Partners GP LP, Partners GP and Onex. As
discussed above, such shares constitute 10.6% of the Issuer's shares of Ordinary
Common Stock assuming conversion of all of the Reporting Person's shares of MV
Common Stock into Ordinary Common Stock and conversion of 4,209,000 shares of MV
Common Stock into Ordinary Common Stock and subsequent sale thereof by the
Reporting Persons on May 20, 2005, pursuant to an underwritten offering and
conversion of 537,500 shares of MV Common Stock into Ordinary Common Stock and
subsequent sale thereof by the Reporting Person on June 7, 2005, pursuant to an
underwritten offering (assuming 26,936,530 additional shares of Ordinary Common
Stock outstanding prior to the offerings). Mr. Schwartz may be deemed a
beneficial owner of the shares of Ordinary Common Stock beneficially owned by
the other Reporting Persons but disclaims beneficial ownership of such shares.

            (c) On May 11, 2005, Holdings purchased 3,613 shares of MV Common
Stock from the Issuer that it was required to purchase under the Issuer's Plan
of Reorganization in connection with a prior quarterly resolution of disputed
claims of certain of Issuer's creditors for a price of $9.78 per share, in a
private transaction. On May 20, 2005, Holdings sold 4,209,000 shares of MV
Common Stock in an underwritten offering. On June 7, 2005, Holdings sold 537,500
shares of MV Common Stock in an underwritten offering. Except as described
herein, no Reporting Person has effected any transaction in shares of Ordinary
Common Stock during the preceding 60 days.

            (d) To the best knowledge of the Reporting Persons, no person other
than the Reporting Persons has the right to receive or the power to direct the
receipt of dividends from, or the proceeds from the sale of, shares of Ordinary
Common Stock or MV Common Stock, except that limited partners of the Reporting
Persons may receive distributions including a portion of such dividends or
proceeds.

            (e) Not applicable.

Item 7. Material to Be Filed as Exhibits.

      1.    Joint Filing Agreement incorporated by reference to the Statement on
            Schedule 13D of Magellan Health Services Inc. filed with the
            Securities and Exchange Commission by Magellan Holdings LP, Onex
            Partners LP, Onex Partners GP LP, Onex Partners GP Inc., Onex
            Corporation and Mr. Gerald W. Schwartz on January 16, 2004.

      2.    Amended and Restated Certificate of Incorporation of Magellan Health
            Services, Inc., as in effect on January 5, 2004, (incorporated by
            reference to Exhibit 2.9 to the Form 8-K filed with the Securities
            and Exchange Commission by the Issuer on January 6, 2004).

      3.    Registration Rights Agreement, dated as of January 5, 2004, among
            Magellan Health Services, Inc., Magellan Holdings LP and Aetna, Inc.
            (incorporated by reference to Exhibit 2.15 to the Form 8-K filed
            with the Securities and Exchange Commission by the Issuer on January
            6, 2004).

      4.    Power of Attorney incorporated by reference to the Amendment to Form
            4 for Dura Automotive Systems, Inc. filed with the Securities and
            Exchange Commission by Gerald W. Schwartz on September 10, 1996.

                               Page 9 of 12 Pages



                                    SIGNATURE

            After reasonable inquiry and to the best of my knowledge and belief,
I hereby certify that the information set forth in this statement is true,
complete and correct.

Dated:   June 13, 2005

                              MAGELLAN HOLDINGS LP

                              By: ONEX PARTNERS GP LP, its General Partner

                                  By: ONEX PARTNERS GP INC., its General Partner

                              By: /s/ Anthony Munk
                                  ----------------------------------------------
                                  Name: Anthony Munk
                                  Title: Vice President

                              ONEX PARTNERS LP

                              By: ONEX PARTNERS PARTNERS GP LP, its General
                                  Partner

                                  By: ONEX PARTNERS GP INC., its General Partner

                              By: /s/ Anthony Munk
                                  ----------------------------------------------
                                  Name: Anthony Munk
                                  Title: Vice President

                              ONEX PARTNERS GP LP

                              By: ONEX PARTNERS GP INC., its General Partner

                                  By: /s/ Anthony Munk
                                  ----------------------------------------------
                                  Name: Anthony Munk
                                  Title: Vice President

                              ONEX PARTNERS GP INC.

                              By: /s/ Anthony Munk
                                  ----------------------------------------------
                                  Name: Anthony Munk
                                  Title: Vice President

                              ONEX CORPORATION

                              By: /s/ Donald Lewtas
                                  ----------------------------------------------
                                  Name: Donald Lewtas
                                  Title: Authorized Signatory

                              Page 10 of 12 Pages



                              GERALD W. SCHWARTZ

                              By: /s/ Donald Lewtas
                                  ----------------------------------------------
                              Name: Donald Lewtas
                              Title: Authorized Signatory for GERALD W. SCHWARTZ

                              Page 11 of 12 Pages



                                INDEX TO EXHIBITS



                                                                           Page No. in Sequential Numbering
Exhibit                                                                                 System
-------                                                                    --------------------------------
                                                                     
  1.          Joint Filing Agreement incorporated by reference to
              the Statement on Schedule 13D of Magellan Health
              Services Inc. filed with the Securities and Exchange
              Commission by Magellan Holdings LP, Onex Partners
              LP, Onex Partners GP LP, Onex Partners GP Inc., Onex
              Corporation and Mr. Gerald W. Schwartz on January
              16, 2004.

  2.          Amended and Restated Certificate of Incorporation of
              Magellan Health Services, Inc., as in effect on January 5,
              2004, (incorporated by reference to Exhibit 2.9 to the
              Form 8-K filed with the Securities and Exchange Commission
              by the Issuer on January 6, 2004).

  3.          Registration Rights Agreement, dated as of January 5,
              2004, among Magellan Health Services, Inc., Magellan
              Holdings LP and Aetna, Inc. (incorporated by reference to
              Exhibit 2.15 to the Form 8-K filed with the Securities and
              Exchange Commission by the Issuer on January 6, 2004).

  4.          Power of Attorney incorporated by reference to the
              Amendment to Form 4 for Dura Automotive Systems, Inc.
              filed with the Securities and Exchange Commission by
              Gerald W. Schwartz on September 10, 1996.


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