EXHIBIT 15.1

September 3, 2003

The Board of Directors and Stockholders, Sun Microsystems, Inc.

We are aware of the incorporation by reference in the Registration Statement (Form S-8) of Sun Microsystems, Inc. pertaining to the CenterRun, Inc., 2000 Equity Incentive Plan of our reports dated October 17, 2002, January 15, 2003 and April 15, 2003, relating to the unaudited condensed consolidated interim financial statements of Sun Microsystems, Inc. that are included in its Form 10-Q for the quarters ended September 29, 2002, December 29, 2002 and March 30, 2003.

Pursuant to Rule 436(c) of the Securities Act of 1933 our reports are not a part of the registration statement prepared or certified by accountants within the meaning of Section 7 or 11 of the Securities Act of 1933.

Very truly yours,

/s/ Ernst & Young LLP