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 March, 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: March 23, 2006	By:	/s/ Takashi Shoda
	Name:	Takashi Shoda
	Title:	President and Representative Director

EXHIBIT INDEX

Exhibit Number		Description of Exhibit
99.1	—	Press Release: “American Subsidiaries of Daiichi Pharmaceutical and Sankyo to Integrate”

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

American Subsidiaries of Daiichi Pharmaceutical and Sankyo to Integrate

Tokyo, March 23, 2006 – DAIICHI SANKYO COMPANY, LIMITED has announced today the upcoming business integration of the American subsidiaries of Sankyo Co., Ltd. and Daiichi Pharmaceutical Co., Ltd. The newly formed company will commence business on April 3, 2006, under the name, DAIICHI SANKYO, INC. (DSI).

DSI will possess an R&D and sales division, and will be central to DAIICHI SANKYO’s growth strategy by assuming responsibility for the Group’s new drug development and sales in the United States.

1. Newly Integrated Organization

2. New Company Profile

(1) Company name: DAIICHI SANKYO, INC. (DSI)

(2) Establishment date: October 22, 1996

(3) Capital: $24,985,125

(4) Outstanding shares: 24.75 stocks

(5) Ratio of shareholdings: Sankyo 80.8%; Daiichi Pharmaceutical 19.2%

(6) Corporate officers: Joseph P. Pieroni (President), Hiroshi Hashimoto (financial officer), Craig B. Bleifer (secretarial officer)

(7) Directors: John C. Alexander (Chairman of the Board of Directors), Joseph P. Pieroni, Hiroyoshi Horikoshi, Kazunori Hirokawa, Hiroshi Hashimoto, Hikaru Nagata, Masatoshi Sakamoto

(8) Main businesses: Research, development and sales of pharmaceuticals

(9) Main office location: Two Hilton Court, Parsippany, New Jersey 07054, USA

(10) Fiscal year ending March 31

(11) Date of business commencement: Monday, April 3, 2006

3. Integration Method

Daiichi Pharmaceutical’s American subsidiary, Daiichi Pharma Holdings, Inc., shall be merged into the surviving company, Sankyo’s American subsidiary, Sankyo Pharma Inc. The company name shall be changed to DAIICHI SANKYO, INC.