SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

_________

FORM 6-K

Report of Foreign Private Issuer
Pursuant to Rule 13a-16 or 15d-16 of the

Securities Exchange Act of 1934

For the month of May 2007

Commission File Number 1-31927

_________

NORTHERN ORION RESOURCES INC.

(Translation of registrant’s name into English)

Suite 250 - 1075 West Georgia Street

Vancouver, British Columbia, Canada V6E 3C9

(Address of principal executive office)

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 Form 40-F X

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):_____

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):_____

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 X

Form 52-109F2 Certification of Interim Filings

I, David W. Cohen, President and Chief Executive Officer, of Northern Orion Resources Inc., certify that:

1. I have reviewed the interim filings (as this term is defined in Multilateral Instrument 52-109 Certification of Disclosure in Issuers’ Annual and Interim Filings) of Northern Orion Resources Inc., (the “Issuer”) for the interim period ending March 31, 2007;

2. Based on my knowledge, the interim filings do not contain any untrue statement of a material fact or omit to state a material fact required to be stated or that is necessary to make a statement not misleading in light of the circumstances under which it was made, with respect to the period covered by the interim filings;

3. Based on my knowledge, the interim financial statements together with the other financial information included in the interim filings fairly present in all material respects the financial condition, results of operations and cash flows of the Issuer, as of the date and for the periods presented in the interim filings;

4. The Issuer's other certifying officers and I are responsible for establishing and maintaining disclosure controls and procedures and internal control over financial reporting for the Issuer, and we have:

(a) designed such disclosure controls and procedures, or caused them to be designed under our supervision, to provide reasonable assurance that material information relating to the Issuer, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which the interim filings are being prepared; and

(b) designed such internal control over financial reporting, or caused it to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with the Issuer’s GAAP; and

5. I have caused the Issuer to disclose in the interim MD&A any change in the Issuer’s internal control over financial reporting that occurred during the Issuer’s most recent interim period that has materially affected, or is reasonably likely to materially affect, the Issuer’s internal control over financial reporting.

Date:

May 10, 2007

/s/David W. Cohen______________

David W. Cohen

President and Chief Executive Officer

Form 52-109F2 Certification of Interim Filings

I, Horng Dih Lee, Chief Financial Officer, of Northern Orion Resources Inc., certify that:

Date:

May 10, 2007

/s/Horng Dih Lee_______________

Horng Dih Lee

Chief Financial Officer

SIGNATURE

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.

NORTHERN ORION RESOURCES INC.

(Registrant)

Date:

May 11, 2007

By:

/s/David W. Cohen

David W. Cohen
President and Chief Executive Officer

NORTHERN ORION RESOURCES INC 6-K