6-K

FORM 6-K

SECURITIES AND EXCHANGE COMMISSION

450, 5th Street

Washington, D.C. 20549

REPORT OF FOREIGN PRIVATE ISSUER

Pursuant to Rule 13a-16 or 15d-16 of

the Securities Exchange Act of 1934

For the month of August, 2006

Daiichi Sankyo Company, Limited

(Translation of registrant’s name into English)

5-1, Nihonbashi 3-chome

Chuo-ku, Tokyo 103-8426

Japan

(Address of principal executive offices)

Indicate by check mark whether the registrant files or will file annual reports under cover Form 20-F or Form 40-F.

Form 20-F  þ            Form 40-F  ¨

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(1):

Yes  ¨            No  þ

Indicate by check mark if the registrant is submitting the Form 6-K in paper as permitted by Regulation S-T Rule 101(b)(7):

Yes  ¨            No  þ

Indicate by check mark whether the registrant by furnishing the information contained in this Form is also thereby furnishing the information to the Commission pursuant to Rule 12g3-2(b) under the Securities Exchange Act of 1934.

Yes  ¨            No  þ

If “Yes” is marked, indicate below the file number assigned to the registrant in connection with Rule 12g3-2(b): N/A

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

	DAIICHI SANKYO COMPANY, LIMITED
DATE: August 2, 2006	By:	/s/ Takashi Shoda
	Name:	Takashi Shoda
	Title:	President and Representative Director

EXHIBIT INDEX

Exhibit Number		Description of Exhibit
99.1	—	Sankyo Commences Patent Litigation against Benicar® ANDA Filing in the United States

EX-99.1

Exhibit 99.1

For Immediate Release

Company name: DAIICHI SANKYO COMPANY, LIMITED

Representative: Takashi Shoda, President and Representative Director

(Code no.: 4568, First Section, Tokyo, Osaka and Nagoya Stock Exchanges)

Please address inquiries to Toshio Takahashi, Corporate Officer in Charge,

Corporate Communications Department

Telephone: +81-3-6225-1126

http://www.daiichisankyo.co.jp/

SANKYO COMMENCES PATENT LITIGATION AGAINST BENICAR^® ANDA

FILING IN THE UNITED STATES

Tokyo, August 2, 2006 — DAIICHI SANKYO COMPANY, LIMITED announces that SANKYO COMPANY, LIMITED (President: Ikegami, Yasuhiro; hereinafter “Sankyo”), a wholly owned subsidiary of DAIICHI SANKYO COMPANY, LIMITED, and its U.S. subsidiary, DAIICHI SANKYO, INC. (New Jersey, hereinafter “DSI”), commenced litigation against Mylan* in the United States District Court for the District of New Jersey for infringement of Sankyo’s U.S. patent (hereinafter “Patent”) covering olmesartan medoxomil, the active ingredient in Sankyo’s antihypertensive drug, Benicar^®. Mylan has filed an Abbreviated New Drug Application (“ANDA”) with the Food and Drug Administration seeking to market a generic version of Benicar^®.

Sankyo and DSI believe that the Patent, which expires in April 2016 in the United States, is valid and intends to vigorously defend the Patent.

Benicar^® is an angiotensin II receptor antagonist that Sankyo independently developed, and is marketed in over 35 countries as an antihypertensive drug which suppresses vasoconstriction by affecting the rennin-angiotensin system to control blood pressure.

*Note:

“Mylan” refers to Mylan Pharmaceuticals, Inc. (HQ: West Virginia) and its parent company, Mylan Laboratories, Inc. (HQ: Pennsylvania).