U.S. Xpress Enterprises (USX) 10-Q 2006 Q1 Quarterly report

Exhibit 32.1

CERTIFICATION PURSUANT TO 18 U.S.C. SECTION 1350 AS ADOPTED

PURSUANT TO SECTION 906 OF THE SARBANES-OXLEY ACT OF 2002

In connection with the Quarterly Report of U.S. Xpress Enterprises, Inc. (the “Company”) on Form 10-Q for the quarterly period ended March 31, 2006, as filed with the Securities and Exchange Commission on the date hereof (the “Report”), the undersigned hereby certifies, pursuant to 18 U.S.C. Section 1350 (as adopted pursuant to Section 906 of the Sarbanes-Oxley Act of 2002), that he is the Chief Executive Officer of the Company and that: (1) the Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and (2) the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company.

/s/ Max L. Fuller  

Max L. Fuller, Chief Executive Officer

Date: May 10, 2006