UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

Washington, D.C. 20549

FORM 10-K/A

Amendment No. 1

(Mark one)

For the fiscal year ended March 31, 2012

For the transition period from              to              

Commission File No: 0-11740

MESA LABORATORIES, INC.

(Exact name of registrant as specified in its charter)

Registrant’s telephone number, including area code: (303) 987-8000

Securities registered under Section 12(b) of the Act:

Securities registered under Section 12(g) of the Act: None

Indicate by check mark if the registrant is a well-known seasoned issuer, as defined in Rule 405 of the Securities Act. YES o NO x

Indicate by check mark if the registrant is not required to file reports pursuant to Section 13 or Section 15(d) of the Act. YES o NO x

Indicate by check mark whether the registrant (1) has filed all reports to be filed by Section13 or 15(d) of the Securities Exchange Act of 1934 during the proceeding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days. YES x NO o

Indicate by check mark whether the registrant has submitted electronically and posted on its corporate Web site, if any, every Interactive Data File required to be submitted and posted pursuant to Rule 405 of Regulation S-T (Section 232.405 of the chapter) during the preceding 12 months (or for such shorter period that the registrant was required to submit and post such files). YES x NO o

Indicate by check mark if disclosure of delinquent filers pursuant to Item 405 of Regulation S-K is not contained herein, and will not be contained, to the best of registrant’s knowledge, in definitive proxy or information statements incorporated by reference in Part III of the Form 10-K or any amendment to this Form 10-K. x

Indicate by check mark whether the registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer or a smaller reporting company. See definitions of “large accelerated filer,” “accelerated filer” and “smaller reporting company” in Rule 12b-2 of the Exchange Act. (check one):

Indicate by check mark whether the registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act). YES o NO x

The aggregate market value, as of September 30, 2011, (the last business day of the registrant’s most recently completed second fiscal quarter) of the voting and non-voting common equity of Mesa Laboratories Inc. held by non-affiliates (assuming, for this purpose, that all directors, officers and owners of 5% or more of the registrant’s common stock are deemed affiliates) computed by reference to the price at which the common equity was last sold ($35.34 per share) was approximately $63,983,440.

The number of outstanding shares of the common stock as of May 31, 2012 was 3,343,731.

DOCUMENTS INCORPORATED BY REFERENCE

Proxy Statement for the 2012 Annual Meeting of Shareholders

Part III information is incorporated by reference from the Proxy Statement

EXPLANATORY NOTE

This Amendment No. 1 on Form 10-K/A to our Annual Report on Form 10-K for the fiscal year ended March 31, 2012, originally filed with the Securities and Exchange Commission on June 29, 2012, amends Item 9A(T) (Controls and Procedures) of our Annual Report on Form 10-K.  This Form 10-K/A is filed to correct format and completeness of the disclosure.  Consent of our independent auditors is attached to this Form 10-K/A as Exhibit 23.1 and certifications from our Chief Executive Officer and Chief Financial Officer required by Sections 302 and 906 of the Sarbanes-Oxley Act of 2002 are attached to this Form 10-K/A as Exhibits 31.1, 31.2, 32.1 and 32.2.

This Amendment No. 1 amends and restates in its entirety Item 9 A(T) and the Exhibit Index of the Original Filing. This Amendment No. 1 does not modify or update other disclosures in the Original Filing, and, accordingly, this Amendment No. 1 should be read in conjunction with the Original Filing.

ITEM 9A(T).  CONTROLS AND PROCEDURES

Evaluation of Disclosure Controls and Procedures

We carried out an evaluation as of the last day of the period covered by this Annual Report on Form 10-K, under the supervision and with the participation of our management, including our Chief Executive Officer and Chief Financial Officer, of the effectiveness of the design and operation of our disclosure controls and procedures as defined in Rules 13a-15(e) and 15d-15(e) of the Securities Exchange Act of 1934 (“Exchange Act”). Based upon that evaluation, the Chief Executive Officer and Chief Financial Officer concluded that our disclosure controls and procedures (a) are effective to ensure that information required to be disclosed by us in reports filed or submitted under the Exchange Act is timely recorded, processed, summarized and reported and (b) include, without limitation, controls and procedures designed to ensure that information required to be disclosed by us in reports filed or submitted under the Exchange Act is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate to allow timely decisions regarding required disclosure.

Management’s Report on Internal Control over Financial Reporting

Our management, including our Chief Executive Officer and Chief Financial Officer, is responsible for establishing and maintaining adequate internal control over financial reporting as required by Sarbanes-Oxley (SOX) Section 404.A.  Our internal control over financial reporting is a process designed to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements in accordance with generally accepted accounting principles in the United States.  Because of its inherent limitations, internal control over financial reporting may not prevent or detect misstatements.  Therefore, even those systems determined to be effective can provide only reasonable assurance of achieving their control objectives.  Management evaluated the effectiveness of our internal control over financial reporting based on the framework in “Internal Control — Integrated Framework” issued by the Committee of Sponsoring Organizations of the Treadway Commission (COSO).

Our management evaluated, with the participation of our Chief Executive Officer and Chief Financial Officer, the effectiveness of the design and operation of our internal control over financial reporting as of March 31, 2012. Based on that evaluation, our management concluded that our internal control over financial reporting was effective at March 31, 2012.

This annual report does not include an attestation report of our registered public accounting firm regarding internal control over financial reporting.  Management’s report was not subject to attestation by our registered public accounting firm pursuant to temporary rules of the Securities and Exchange Commission that permit us to provide only management’s report in this annual report.

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Changes in internal control over financial reporting

There was no change in our internal control over financial reporting that occurred during our fourth quarter of the year ended March 31, 2012, that has materially affected, or is reasonably likely to materially affect our internal control over financial reporting.  Due to growth and recent acquisitions, we have added resources to our organization and we are performing a comprehensive review of all of our controls and procedures, with the assistance of a third party.  We are upgrading our ERP system, including a full evaluation of segregation of duties and application access controls.  We will continue to monitor and evaluate the effectiveness of our internal controls and procedures over financial reporting, and are committed to implementing improvements, as necessary.

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SIGNATURES

In accordance with Section 13 or 15(d) of the Exchange Act, the registrant caused this report to be signed on its behalf by the undersigned, thereunto duly authorized.

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EXHIBITS INDEX

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