EXHIBIT 31.1**CERTIFICATION PURSUANT TO SECTION 302 OF THE SARBANES-OXLEY ACT OF 2002**I, Keith A. Katkin, certify that:1. I have reviewed this quarterly report on Form 10-Q of Avanir Pharmaceuticals; 2. Based on my knowledge, this 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 of the circumstances under which such statements were made, not misleadingwith respect to the period 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 financialcondition, results of operations and cash flows of the registrant as of, and for, theperiods presented in this report; 4. The registrant’s other certifying officer(s) and I are responsible for establishingand maintaining disclosure controls and procedures (as defined in Exchange Act Rules13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined inExchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:     a) Designed such disclosure controls and procedures, or caused such disclosure controls andprocedures to be designed under our supervision, to ensure that material information relating tothe registrant, including its consolidated subsidiaries, is made known to us by others within thoseentities, particularly during the period in which this report is being prepared;     b) Designed such internal control over financial reporting, or caused such internal controlover financial reporting to be designed under our supervision, to provide reasonable assuranceregarding the reliability of financial reporting and the preparation of financial statements forexternal purposes in accordance with generally accepted accounting principles;     c) Evaluated the effectiveness of the registrant’s disclosure controls and procedures andpresented in this report our conclusions about the effectiveness of the disclosure controls andprocedures, 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 financialreporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourthfiscal quarter in the case of an annual report) that has materially affected, or is reasonablylikely to materially affect, the registrant’s internal control over financial reporting; and5. The registrant’s other certifying officer(s) and I have disclosed,based on our most recent evaluation of internal control over financialreporting, to the registrant’s auditors and the audit committee ofregistrant’s Board of Directors (or persons performing the equivalentfunctions):     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’sability to record, process, summarize and report financial information; and     b) Any fraud, whether or not material, that involves management or other employees who have asignificant role in the registrant’s internal control over financial reporting.        Dated: August 9, 2007 /s/ Keith A. Katkin   Keith A. Katkin   President and Chief Executive Officer[Principal Executive Officer]