Objective To establish the Chinese Evidence-Based Medicine/Cochrane Centre Database of Clinical Trials and Diagnostic Tests to provide reliable scientific data for clinical practice, teaching, research and systematic reviewers and submit the results of randomised controlled trials (RCTs) and controlled clinical trials (CCTs) to The Cochrane Collaboration. Methods Data were collected by handsearching and electronic searching based on the criterion of the Collaboration and clinical epidemiology. Results Up to December 2003, there were 16 652 RCTs /CCTs and 3 786 DT included in the database. A total of 4 966 RCTs and CCTs were submitted to the Collaboration. Nineteen specialized databases were set up. Conclusions The first phase of the Chinese Evidence-Based Medicine/Cochrane Centre Database of Clinical Trials and Diagnostic Tests has been completed. The database has provided advice for contributiors both at home and abroad.