EXHIBIT 32.1
SECTION 1350 CERTIFICATION BY THE CHIEF EXECUTIVE OFFICER
I, Timothy W. Byrne, Chief Executive Officer of United States Lime & Minerals, Inc. (the “Company”), hereby certify that, to my knowledge:
| (1) | | The Company’s periodic report on Form 10-Q for the quarterly period ended September 30, 2007 (the “Form 10-Q”) fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934, as amended; and |
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| (2) | | The information contained in the Form 10-Q fairly presents, in all material respects, the financial condition and results of operations of the Company. |
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| Dated: November 5, 2007 | /s/ Timothy W. Byrne | |
| | Timothy W. Byrne | |
| | President and Chief Executive Officer | |
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