Exhibit 31.1**CERTIFICATION**I, Michael D. Watford, Chairman, President and Chief Executive Officer of Ultra Petroleum Corp.certify that: 1. I have reviewed this quarterly report on Form 10-Q of Ultra Petroleum Corp.;  2. Based on my knowledge, this report does not contain any untrue statement of a materialfact or omit to state a material fact necessary to make the statements made, in light ofthe circumstances under which such statements were made, not misleading with respect to theperiod covered by this report;  3. Based on my knowledge, the financial statements, and other financial informationincluded in this report, fairly present in all material respects the financial condition,results of operations and cash flows of the registrant as of, and for, the periodspresented in this report;  4. I am responsible for establishing and maintaining disclosure controls and procedures(as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control overfinancial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for theregistrant and have: a. Designed such disclosure controls and procedures, or caused suchdisclosure controls and procedures to be designed under our supervision, toensure that material information relating to the registrant, including itsconsolidated subsidiaries, is made known to us by others within those entities,particularly during the period in which this report is being prepared;  b. Designed such internal control over financial reporting, orcaused such internal control over financial reporting to be designed under oursupervision, to provide reasonable assurance regarding the reliability offinancial reporting and the preparation of financial statements for externalpurposes in accordance with generally accepted accounting principles;  c. Evaluated the effectiveness of the registrant’s disclosurecontrols and procedures and presented in this report our conclusions about theeffectiveness of the disclosure controls and procedures, as of the end of theperiod covered by this report based on such evaluation; and  d. Disclosed in this report any change in the registrant’s internalcontrol over financial reporting that occurred during the registrant’s mostrecent fiscal quarter (the registrant’s fourth fiscal quarter in the case of anannual report) that has materially affected, or is reasonably likely tomaterially affect, the registrant’s internal control over financial reporting;and 5. I have disclosed, based on my most recent evaluation of internal control over financialreporting, to the registrant’s auditors and the audit committee of the registrant’s boardof directors (or persons performing the equivalent functions): a. All significant deficiencies and material weaknesses in thedesign or operation of internal control over financial reporting which arereasonably 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 orother employees who have a significant role in the registrant’s internal controlover financial reporting.        Dated: October 28, 2005 By:  /s/Michael D. Watford   Michael D. Watford    Chairman, President and Chief Executive Officer