This study examines the association between auditor type (public versus private) and earnings quality as measured by the levels of discretionary accruals in Iran. This study hypothesize that there is no significant difference in discretionary accruals between public and private sector audit firms when there is low incentives for auditors to provide high-quality audits in Iran. Using a sample of listed firms in the Tehran Stock Exchange from 1998-2003 (1378-1383)، this study finds that there is no significant difference between discretionary accruals of firms with a public sector auditor and firms with a private sector auditor. This result implies that there may be no significant difference in audit quality between public and private sector audits. Partitioning the sample into sub-periods to examine the effect of increased competition، as a result of establishing the Iranian Certified Public Accountants (ICPA) in 2001(1381)، on audit quality، this study finds some evidences of an increase in the levels of discretionary accruals of firms with a public sector auditor. This is consistent with the argument that increased competition in the audit market which may reduce the quality of audits.