SEC Form 4

FORM 4		UNITED STATES SECURITIES AND EXCHANGE COMMISSION Washington, D.C. 20549 STATEMENT OF CHANGES IN BENEFICIAL OWNERSHIP Filed pursuant to Section 16(a) of the Securities Exchange Act of 1934 or Section 30(h) of the Investment Company Act of 1940	OMB APPROVAL OMB Number: 3235-0287 Estimated average burden hours per response: 0.5
X	Check this box if no longer subject to Section 16. Form 4 or Form 5 obligations may continue. See Instruction 1(b).

1. Name and Address of Reporting Person* PIEN HOWARD H (Last) (First) (Middle) 6 CARRIAGE HOUSE COURT (Street) CHERRY HILL NJ 08003 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol IMMUNOGEN INC [ IMGN ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) Director 10% Owner Officer (give title below) X Other (specify below) Former Director
	3. Date of Earliest Transaction (Month/Day/Year) 05/16/2007
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) X Form filed by One Reporting Person Form filed by More than One Reporting Person

Table I - Non-Derivative Securities Acquired, Disposed of, or Beneficially Owned
1. Title of Security (Instr. 3)	2. Transaction Date (Month/Day/Year)	2A. Deemed Execution Date, if any (Month/Day/Year)	3. Transaction Code (Instr. 8)		4. Securities Acquired (A) or Disposed Of (D) (Instr. 3, 4 and 5)			5. Amount of Securities Beneficially Owned Following Reported Transaction(s) (Instr. 3 and 4)	6. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	7. Nature of Indirect Beneficial Ownership (Instr. 4)
			Code	V	Amount	(A) or (D)	Price
Common Stock	05/16/2007		M		2,168	A	$5.03	2,168	D

Table II - Derivative Securities Acquired, Disposed of, or Beneficially Owned (e.g., puts, calls, warrants, options, convertible securities)
1. Title of Derivative Security (Instr. 3)	2. Conversion or Exercise Price of Derivative Security	3. Transaction Date (Month/Day/Year)	3A. Deemed Execution Date, if any (Month/Day/Year)	4. Transaction Code (Instr. 8)		5. Number of Derivative Securities Acquired (A) or Disposed of (D) (Instr. 3, 4 and 5)		6. Date Exercisable and Expiration Date (Month/Day/Year)		7. Title and Amount of Securities Underlying Derivative Security (Instr. 3 and 4)		8. Price of Derivative Security (Instr. 5)	9. Number of derivative Securities Beneficially Owned Following Reported Transaction(s) (Instr. 4)	10. Ownership Form: Direct (D) or Indirect (I) (Instr. 4)	11. Nature of Indirect Beneficial Ownership (Instr. 4)
				Code	V	(A)	(D)	Date Exercisable	Expiration Date	Title	Amount or Number of Shares
Deferred Share Unit	$0(1)	05/16/2007		M			2,168	(2)(3)	(2)	Common Stock(2)	2,168	$0(1)	2,168	D

Explanation of Responses:

1. The deferred share units were issued pursuant to the Issuer's 2004 Non-Employee Director Compensation and Deferred Share Unit Plan, as amended, and are convertible into Common Stock on a one-to-one basis.

2. On May 16, 2007, the reporting person resigned from the Board of Directors, and as a result, the vested deferred share units are settled 100% in shares of Common Stock of the Company. The unvested portions of the deferred share units have expired by their terms.

3. The deferred share units are fully vested. The reporting person received 131, 862, and 18 deferred share units on Februray 14, 2007, May 14, 2007, and May 16, 2007, respectively, which vested immediately. The reporting person also received a grant on January 31, 2007 for 13,888 deferred share units, which vested ratably over a three year period in quarterly increments at the end of each quarter, of which 1,157 shares were fully vested upon the reporting person's resignation.

	/s/ Daniel M. Junius	05/18/2007
	** Signature of Reporting Person	Date
Reminder: Report on a separate line for each class of securities beneficially owned directly or indirectly.
* If the form is filed by more than one reporting person, see Instruction 4 (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).
Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, see Instruction 6 for procedure.
Persons who respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB Number.