[The aim and features of clinical database].
Clinical database is a project aiming at quality improvement in medicine. It combines systematic collection of clinical data, analysis and feedback to medical practitioners. Medical professionals can clarify their challenges and deal with quality improvement based on feedback. Large and comprehensive clinical databases have been founded in many countries recently. The databases can be used for various purposes; quality indicator, support tool for medical decision-making, policy decision-making and evaluation, clinical research and public reporting. Administrators must pay attention to scientific, ethical and political perspectives. In this manuscript, the authors discussed definitions and issues of large clinical databases.