Ownership Submission
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
OMB APPROVAL
OMB Number: 3235-0104
Expires: January 31, 2005
Estimated average burden hours per response... 0.5

(Print or Type Responses)
1. Name and Address of Reporting Person *
  Baker Bros. Advisors (GP) LLC
 2. Date of Event Requiring Statement (Month/Day/Year)
07/01/2013		 3. Issuer Name and Ticker or Trading Symbol
SEATTLE GENETICS INC /WA [SGEN]
(Last)
(First)
(Middle)
667 MADISION AVENUE 21ST FLOOR		 4. Relationship of Reporting Person(s) to Issuer
(Check all applicable)
__X__ Director __X__ 10% Owner
_____ Officer (give title below) _____ Other (specify below)
5. If Amendment, Date Original Filed(Month/Day/Year)
(Street)

NEW YORK, NY US 10065		 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)
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 control number.

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

Reporting Owners

Reporting Owner Name / Address Relationships
Director 10% Owner Officer Other
Baker Bros. Advisors (GP) LLC
667 MADISION AVENUE 21ST FLOOR
NEW YORK, NY US 10065		   X   X    

Signatures

BAKER BROS. ADVISORS (GP), LLC Name: Scott L. Lessing, Title: President /s/ Scott L. Lessing 07/11/2013
**Signature of Reporting Person Date

Explanation of Responses:

No securities are beneficially owned

* 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).
 
Remarks:
Remarks:
On July 1, 2013, a Certificate of Conversion was filed with the State of Delaware to convert Baker Bros. Advisors, LLC from a limited liability company into a limited partnership named Baker Bros. Advisors LP (the "Adviser"), with Baker Bros. Advisors (GP) LLC (the "Adviser GP") as the Adviser's sole general partner.    As the Adviser previously reported on its Form 4 filed on May 21, 2013, the Adviser and, collectively, therefore, its general partner have voting and dispositive power over securities held by its clients Baker Brothers Life Sciences, L.P., 14159, L.P., and 667, L.P. (the "Funds"), but neither the Adviser nor the Adviser GP have a pecuniary interest in such securities, as the Adviser may only receive a portion of the asset-based management fee. Julian C. Baker and Felix J. Baker each may be deemed to control the Adviser GP.  For purposes of Section 16 of the Securities Exchange Act of 1934, as amended, Baker Bros. Advisors (GP) LLC is deemed a director by deputization by virtue of its representation on the Board of Directors of Seattle Genetics, Inc.

Note: File three copies of this Form, one of which must be manually signed. If space is insufficient, See Instruction 6 for procedure.

Potential persons who are to respond to the collection of information contained in this form are not required to respond unless the form displays a currently valid OMB number.