The European audit reform contains the implementation of an external mandatory auditor rotation (audit firm rotation) and a separation of audit and non audit duties to increase auditor independence. The central question is, whether these regulation measures are connected with an increased accounting and audit quality. First, this article presents an agency theoretical foundation of auditor independence. Then, a state of the art analysis of empirical research illustrates these ambivalent results, so that the economic need for the audit market regulation in Europe is controversial.