**Exhibit 31.1****CERTIFICATIONS**I, Patrick K. Donnelly, certify that:     1. I have reviewed this quarterly report on Form 10-Q of PRA International;     2. Based on my knowledge, this quarterly report does not contain any untrue statement of amaterial fact 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 the periodcovered by this quarterly report;     3. Based on my knowledge, the financial statements, and other financial information includedin this quarterly report, fairly present in all material respects the financial condition, resultsof operations and cash flows of the registrant as of, and for, the periods presented in thisquarterly report;     4. The registrant’s other certifying officer and I are responsible for establishing andmaintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules13a-15(f) and 15d-15(f)) for the registrant and have:     (a) Designed such disclosure controls and procedures, or caused suchdisclosure controls and procedures to be designed under oursupervision, to ensure that material information relating to theregistrant, including its consolidated subsidiaries, is made knownto us by others within those entities, particularly during theperiod in which this quarterly report is being prepared;     (b) Designed such internal control over financialreporting, or caused such internal control over financial reportingto be designed under our supervision, to provide reasonableassurance regarding the reliability of financial reporting and thepreparation of financial statements for external purposes inaccordance with generally accepted accounting principles;     (c) Evaluated the effectiveness of the registrant’s disclosurecontrols and procedures and presented in this report our conclusionsabout the effectiveness of the disclosure controls and procedures,as of the end of the period covered by this quarterly report; and     (d) Disclosed in this quarterly report any change in theregistrant’s internal control over financial reporting that occurredduring the registrant’s most recent fiscal quarter that hasmaterially affected, or is reasonably likely to materially affect,the registrant’s internal control over financial reporting;     5. The registrant’s other certifying officer and I have disclosed, based on our most recentevaluation, to the registrant’s auditors and the audit committee of the registrant’s board ofdirectors (or persons performing the equivalent functions):     (a) All significant deficiencies and material weaknesses in thedesign or operation of internal control over financial reportingwhich are reasonably likely to adversely affect the registrant’sability to record, process, summarize and report financial data; and     (b) Any fraud, whether or not material, that involves management orother employees who have a significant role in the registrant’sinternal control over financial reporting.       Signature:         /s/ Patrick K. Donnelly     Name: Patrick K. Donnelly    Title: Chief Executive Officer  Date: May 5, 2006