EXHIBIT 15.1

Awareness Letter of Deloitte & Touche LLP

Bank of America, N.A. as Trustee
for the Permian Basin Royalty Trust:

We have made a review, in accordance with the standards of the Public Company Accounting Oversight Board (United States), of the unaudited interim financial information of Permian Basin Royalty Trust, for the periods ended June 30, 2006 and 2005, as indicated in our report dated August 7, 2006, because we did not perform an audit, we expressed no opinion on that information.

We are aware that Permian Basin Royalty Trust and Burlington Resources Inc. have incorporated by reference in their Registration Statement No. 333-124056-01 on Form S-3 and that Permian Basin Royalty Trust and ConocoPhillips have incorporated by reference in their Registration Statement No. 333-135160 on Form S-3, Permian Basin Royalty Trust’s Form 10-Q for the quarter ended June 30, 2006, which includes our report dated August 7, 2006, covering the unaudited interim financial information contained therein. We also are aware that the aforementioned report, pursuant to Rule 436(c) of the Securities Act of 1933, that report is not considered a part of the registration statements prepared or certified by an accountant or a report prepared or certified by an accountant within the meaning of Sections 7 and 11 of the Act.

DELOITTE & TOUCHE LLP

Dallas, Texas
August 7, 2006