The complexity of clinical trials has increased significantly during the last two decades. This led to major challenges for quality assurance and control, in particular for multicentre trials. It became apparent that there is a need to complement conventional monitoring at the study sites (on-site monitoring) by new monitoring approaches. Even though central data monitoring (CDM) has become well established in clinical research, the scope and extent of it is not clear among researchers, particularly in the academic setting. This fact sheet examines CDM in detail, describing its contribution to data quality and study oversight as well as its implementation. In addition, it addresses inconsistent terminology and the application of CDM in guidance documents.