Quality management (QM) cannot be successfully implemented and performed without audits. The PDCA (Plan-Do-Check-Act) cycle is the core component of QM systems. In this cycle an audit represents the crucial step "check". Audits verify whether the performed actions and their results conform to the requirements. It is especially important to verify whether the principles of QM are omnipresent and fully implemented in a department or institution. The announcement of an audit may cause mixed feelings or even anxiety among the personnel to be audited. Without previous information and training the audit may be perceived as an act of control and intrusion into departmental affairs. The colleagues often fear sanctions if lapses are found or consider the audit to be a cross-examination. However, an audit is rather meant to be a helpful aid and a chance to continuously improve the departmental QM system by means of a constructive communication among colleagues. In the year 2009 the European Commission published guidelines for the performance of clinical audits in medical radiology, including diagnostic radiology, nuclear medicine and radiation therapy (Council Directive 97 / 43 / EURATOM). The aim is an optimal protection of the individual from the hazards of ionizing radiation and the directive expects radiological departments to perform clinical audits in accordance with national procedures.