Background: Users especially investors, as suppliers of capital and the most important groups of accounting data and financial report, need reliable financial information. In regard to the role of auditors, The present study evaluates the relationship between auditor professional ethics and audit quality.

Method: The research method is descriptive-correlation . The population of study consists  of auditors of the Iranian Society of CPAs. Among all subjects 312 participants were selected by simple random sampling. The instrument was the researcher made  questionnaire. The questionare includes 12 questions for audit quality 12  and 37 questions for auditor professional ethics.  Data were analyzed by multivariate regression.

Results: The results showed that the auditor's straightening to integrity and honesty, independence  and impartiality of the auditor, auditor commitment to professional behavior, auditor commitment to confidentiality and  auditor's professional performance affects on audit quality .

Conclusion: according to the effect of professional ethics on audit quality, it is necessary that  organizations pay more attentions to ethical codes of audit.