FORM 3

UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 INITIAL STATEMENT OF BENEFICIAL OWNERSHIP OF SECURITIES Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934, Section 17(a) of the Public Utility Holding Company Act of 1935 or Section 30(h) of the Investment Company Act of 1940

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(Print or Type Responses)

1. Name and Address of Reporting Person *   MITCHELL DEAN J 2. Date of Event Requiring Statement (Month/Day/Year) 01/30/2012 3. Issuer Name and Ticker or Trading Symbol IMMUNOGEN INC [IMGN] (Last) (First) (Middle) 7 LEONARD COURT 4. Relationship of Reporting Person(s) to Issuer (Check all applicable) __X__ Director _____ 10% Owner _____ Officer (give title below) _____ Other (specify below) 5. If Amendment, Date Original Filed(Month/Day/Year) (Street) PRINCETON, NJ 08540 6. Individual or Joint/Group Filing(Check Applicable Line) _X_ Form filed by One Reporting Person ___ Form filed by More than One Reporting Person (City) (State) (Zip) Table I - Non-Derivative Securities Beneficially Owned

1.Title of Security (Instr. 4) 2. Amount of Securities Beneficially Owned (Instr. 4) 3. Ownership Form: Direct (D) or Indirect (I) (Instr. 5) 4. Nature of Indirect Beneficial Ownership (Instr. 5)

Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.			SEC 1473 (7-02)
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Table II - Derivative Securities Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)

1. Title of Derivative Security (Instr. 4)	2. Date Exercisable and Expiration Date (Month/Day/Year)		3. Title and Amount of Securities Underlying Derivative Security (Instr. 4)		4. Conversion or Exercise Price of Derivative Security	5. Ownership Form of Derivative Security: Direct (D) or Indirect (I) (Instr. 5)	6. Nature of Indirect Beneficial Ownership (Instr. 5)
	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Deferred Share Unit	04/30/2012(2)(3)	  (2)	Common Stock (2)	4,686	$ 0 (1)	D	Â
Stock Option (right to buy)	04/30/2012(4)	01/30/2022	Common Stock	3,066	$ 13.87	D	Â

Reporting Owners

Reporting Owner Name / Address	Relationships
	Director	10% Owner	Officer	Other
MITCHELL DEAN J 7 LEONARD COURT PRINCETON, NJ 08540	  X	Â	Â	Â

Signatures

/s/ Craig Barrows, attorney in fact		02/01/2012
**Signature of Reporting Person		Date

Explanation of Responses:

*	If the form is filed by more than one reporting person, see Instruction 5(b)(v).
**	Intentional misstatements or omissions of facts constitute Federal Criminal Violations. See 18 U.S.C. 1001 and 15 U.S.C. 78ff(a).
(1)	The deferred share units were issued pursuant to the Issuer's Compensation Policy for Non-Employee Directors and are convertible into Common Stock on a one-to-one basis.
(2)	The vested deferred share units are to be settled 100% in shares of the Common Stock of the Company upon the reporting person's retirement from the Board of Directors.
(3)	The deferred share units vest ratably over a three year period in quarterly increments beginning on April 1, 2012, contingent upon the individual remaining a director as of each vesting date.
(4)	Exercisable as to 767 shares commencing on February 1, 2012, 767 shares commencing on May 1, 2012, 766 shares commencing on August 1, 2012 and 766 shares commencing on November 1, 2012, contingent upon the individual remaining a director as of each vesting date.

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