This master-thesis discusses the influence of audit and non-audit services on the independence of the auditor and provides an overview of recent empirical findings on this issue. Auditing standards require auditors to be independent in fact and in appearance. Although the auditing profession faces strict rules, criticism exists about the joint provision of audit and non-audit services to the audit client. Particularly, non-audit services may impair auditor independence because the additional fees generated from consulting services may increase the economic bond between the client and the auditor and therefore create a fee depend-ency. In addition, the role of the auditor may change from a skeptical outside observer to an active participant in the management of the firm.Since many years, empirical studies try to address this issue but they yielded mixed results. Most studies demonstrate, that there is a link between non-audit services and perceived auditor independence. However, these results do not imply, that the auditors? actual objectivity is impaired. Some even document, that the provision of non-audit services creates incentives and advantages for auditors to perform a higher quality audit due to knowledge spillovers from consulting services. The different results can be traced back to different countries, time periods and perceptions of different groups. Therefore it is unclear, if only a negative perception or actually a factual impairment of the independence of the auditor exists.