Using a unique setting in which mandatory audit firm rotation was required from 2006–2010, and in which both audit fees and audit hours were disclosed (South Korea), this study provides empirical evidence of the economic impact of this policy initiative on audit quality, and the associated implications for audit fees. This study compares both pre- and post-policy implementation and, after the implementation of the policy, mandatory long-tenure versus voluntary short-tenure rotation situations. Where audit firms were mandatorily rotated post-policy, we observe that audit quality (measured as abnormal discretionary accruals) did not significantly change compared with pre-2006 long-tenure audit situations and voluntary post-rotation situations. Audit fees in the post-regulation period for mandatorily rotated engagements are significantly larger than in the pre-regulation period, but are discounted compared to audit fees for post-regulation continuing engagements. We also find that the observed increase in audit fees and audit hours in the post-regulation period extends beyond situations where the audit firm was mandatorily rotated, suggesting that the introduction of mandatory audit firm rotation had a much broader impact than the specific instances of mandatory rotation. Data Availability: Most of the financial data used in the present study are available from the KIS Value Database. The data for audit hours and fees were drawn from statements of operating results filed with the Financial Supervisory Services (FSS) in Korea.