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
	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* Baker Brothers Life Sciences Capital (GP), LLC (Last) (First) (Middle) 667 MADISON AVENUE 17TH FLOOR (Street) NEW YORK NY 10021 (City) (State) (Zip)	2. Issuer Name and Ticker or Trading Symbol SEATTLE GENETICS INC /WA [ SGEN ]	5. Relationship of Reporting Person(s) to Issuer (Check all applicable) X Director X 10% Owner Officer (give title below) Other (specify below)
	3. Date of Earliest Transaction (Month/Day/Year) 04/25/2006
	4. If Amendment, Date of Original Filed (Month/Day/Year)	6. Individual or Joint/Group Filing (Check Applicable Line) Form filed by One Reporting Person X 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(1)	04/25/2006		J(2)		353,150	D	$0	0	I	See Footnote(3)
Common Stock	04/25/2006		J(2)		49,807	D	$0	0	I	See footnote(4)
Common Stock	04/25/2006		J(2)		45,090	D	$0	0	I	See footnote(5)
Common Stock	04/25/2006		J(2)		448,047	A	$0	682,908	I	See footnote(6)

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
Common Stock Warrants (right to buy)	$6.25	04/25/2006		J(2)			312,162	07/08/2003	12/31/2011	Common Stock	312,162	$0	0	I	See footnote(3)
Common Stock Warrants (right to buy)	$6.25	04/25/2006		J(2)			42,981	07/08/2003	12/31/2011	Common Stock	42,981	$0	0	I	See footnote(4)
Common Stock Warrants (right to buy)	$6.25	04/25/2006		J(2)		355,143		07/08/2003	12/31/2011	Common Stock	355,143	$0	355,143	I	See footnote(6)
Series A Convertible Preferred Stock	(7)	04/25/2006		J(2)			249,730	(8)	(9)	Common Stock	2,497,300	$0	0	I	See footnote(3)
Series A Convertible Preferred Stock	(7)	04/25/2006		J(2)			34,385	(8)	(9)	Common Stock	343,850	$0	0	I	See footnote(4)
Series A Convertible Preferred Stock	(7)	04/25/2006		J(2)		284,115		(8)	(9)	Common Stock	2,841,150	$0	284,115	I	See footnote(6)

1. Name and Address of Reporting Person* Baker Brothers Life Sciences Capital (GP), LLC (Last) (First) (Middle) 667 MADISON AVENUE 17TH FLOOR (Street) NEW YORK NY 10021 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer X Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Baker Biotech Capital II (GP), LLC (Last) (First) (Middle) 667 MADISON AVE 17TH FLOOR (Street) NEW YORK NY 10021 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Baker Biotech Capital II (Z) (GP), LLC (Last) (First) (Middle) 667 MADISON AVENUE 17TH FLOOR (Street) NEW YORK NY 10021 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* Baker Biotech Capital III (Z) (GP), LLC (Last) (First) (Middle) 667 MADISON AVENUE 17TH FLOOR (Street) NEW YORK NY 10021 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* BAKER JULIAN (Last) (First) (Middle) 667 MADISON AVENUE 17TH FLOOR (Street) NEW YORK NY 10021 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer Director X 10% Owner Officer (give title below) Other (specify below)

1. Name and Address of Reporting Person* BAKER FELIX (Last) (First) (Middle) 667 MADISON AVENUE (Street) NEW YORK NY 10021 (City) (State) (Zip) Relationship of Reporting Person(s) to Issuer X Director X 10% Owner Officer (give title below) Other (specify below)

Explanation of Responses:

1. See Note 1 in Exhibit 99.1.

2. See Note 1 in Exhibit 99.1.

3. See Note 1 in Exhibit 99.1.

4. See Note 1 in Exhibit 99.1.

5. See Note 1 in Exhibit 99.1.

6. See Note 1 in Exhibit 99.1.

7. See Note 1 in Exhibit 99.1.

8. See Note 1 in Exhibit 99.1.

9. See Note 1 in Exhibit 99.1.

	/s/ Julian C. Baker, as Managing Member of Baker Biotech Capital II (GP), LLC	04/28/2006
	/s/ Julian C. Baker, as Managing Member of Baker Biotech Capital II (Z) (GP), LLC	04/28/2006
	/s/ Julian C. Baker, as Managing Member of Baker Biotech Capital III (Z) (GP), LLC	04/28/2006
	/s/ Julian C. Baker, as Managing Member of Baker Brothers Life Sciences Capital (GP), LLC	04/28/2006
	/s/ Julian C. Baker	04/28/2006
	/s/ Felix J. Baker	04/28/2006
	** 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).
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