EXHIBIT 18




May 6, 2002

Board of Directors
Conoco Inc.
600 North Dairy Ashford
Houston, Texas 77079-1175

Dear Directors:

We are providing this letter to you for inclusion as an exhibit to your Form
10-Q filing pursuant to Item 601 of Regulation S-K.

We have been provided a copy of the Company's Quarterly Report on Form 10-Q for
the period ended March 31, 2002. Note 2 therein describes a change in accounting
principle for major maintenance activities from the accrue-in-advance method to
the expense-as-incurred method. It should be understood that the preferability
of one acceptable method of accounting over another for major maintenance
activities has not been addressed in any authoritative accounting literature,
and in expressing our concurrence below we have relied on management's
determination that this change in accounting principle is preferable. Based on
our reading of management's stated reasons and justification for this change in
accounting principle in the Form 10-Q, and our discussions with management as to
their judgment about the relevant business planning factors relating to the
change, we concur with management that such change represents, in the Company's
circumstances, the adoption of a preferable accounting principle in conformity
with Accounting Principles Board Opinion No. 20.

We have not audited any financial statements of the Company as of any date or
for any period subsequent to December 31, 2001. Accordingly, our comments are
subject to change upon completion of an audit of the financial statements
covering the period of the accounting change.

Very truly yours,



PRICEWATERHOUSECOOPERS LLP