**Exhibit 31.1**

**CERTIFICATION**

**PURSUANT TO 17 CFR 240.13a-14**

**PROMULGATED UNDER**

**SECTION 302OF THE SARBANES-OXLEY ACT OF 2002**

I, Terry L. Persinger, certify that: 

1. I have reviewed this annual report on Form 10-K of Mannatech, Incorporated; 

2. Based onmy knowledge, this annual report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleadingwith respect to the period covered by this annual report; 

3. Based on my knowledge, the financial statements, and other financialinformation included in this annual report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this annual report; 

4. The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (asdefined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and we have: 

(a) designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under oursupervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this annual report is being prepared;

(b) designed such internal control over financial reporting, or caused such internal control over financial reportingto be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c) evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in thisannual report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and 

(d) disclosed in this report any change in the registrant’s internal control over financial reporting (as defined in ExchangeAct Rules 13a-15(f) and 15d-15(f)) that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely tomaterially affect, the registrant’s internal control over financial reporting; and 

5. The registrant’s othercertifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of registrant’s Board of Directors (or persons performing theequivalent functions): 

(a) all significant deficiencies and material weaknesses in the design or operation of internalcontrol over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and 

(b) any fraud, whether or not material, that involves management or other employees who have a significant role in theregistrant’s internal control over financial reporting.