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WRITER’S DIRECT NUMBER:

(212) 848-5009

WRITER’S EMAIL ADDRESS:

astolper@shearman.com

March 30, 2011

BY EDGAR

Ms. Sandy Eisen

United States Securities and Exchange Commission

Division of Corporation Finance

450 Fifth Street, N.W.

Washington, D.C. 20549-0405

Tel: (202) 551-3864

Ecopetrol S.A.

Form 20-F for Fiscal Year Ended December 31, 2009

Filed July 15, 2010

File No. 001-34175

Dear Ms. Eisen:

Ecopetrol S.A. (the “Company”) has received a comment letter dated March 18, 2011 from the staff of the Division of Corporation Finance (the “Staff”) of the United States Securities and Exchange Commission (the “Commission”) concerning the Company’s (i) annual report on form 20-F for fiscal year ended December 31, 2009 (the “Form 20-F”), (ii) response letter dated September 28, 2010 to a comment letter dated August 30, 2010 from the Staff and (iii) response letter dated January 19, 2011 to a comment letter dated December 17, 2010 from the Staff. Pursuant to our phone conversation on March 30, 2011, we hereby advise the Staff that the Company will submit a response to the Staff’s letter no later than April 11, 2011.

If you have any questions or wish to discuss any matters relating to the foregoing, please contact me at 212-848-5009 or Adriana M. Echeverri, Chief Financial Officer of the Company, at 011-57-1234-4254.

	Very truly yours,


	/s/ Antonia E. Stolper

cc:	Javier G. Gutiérrez - Chief Executive Officer – Ecopetrol S.A.

Adriana M. Echeverri – Chief Financial Officer – Ecopetrol S.A.

Alejandro Giraldo – Investor Relations – Ecopetrol S.A.

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