The Cochrane Collaboration is an international, non-profit making organisation which aims to help people make well-informed health care decisions. The main objective is to prepare, update, promote and facilitate access to systematic reviews on health care interventions. The main product is The Cochrane Library, a quarterly electronic publication. The principles and structure of the Cochrane Collaboration and the structure and content of the Cochrane Library will be described. The importance of systematic reviews and meta-analyses as sources of information for clinicians will be presented, with special emphasis on the contributions of the Cochrane Collaboration to the speciality of urology.