The ACTION (A Coronary disease Trial Investigating Outcome with Nifedipine GITS) study was an independent, investigator-initiated, multi-national trial comparing nifedipine GITS to placebo in 7665 patients with stable angina pectoris. The trial was sponsored by the manufacturer of the medication concerned. 291 centers in 19 countries participated. Results have been published. We defined quality management (QM) as all activities directed at ensuring data integrity and consistency; and ensuring appropriate trial conduct, including pro-active prevention of deviations from protocol. We describe the QM framework that was adopted for the ACTION trial and the key tools that were used. In the protocol, particular attention was paid to explicit definition of tasks and responsibilities of all participants, and to unequivocal operational definitions of terms such as 'randomized', 'follow-up', etc. that could be applied by investigators, on-site monitors and during data processing at the coordinating centre. A comprehensive clinical trial and study management system based on simultaneous display of scanned documents and data base content had a central role. We describe in detail how compliance with good clinical practice was ensured, how the intention-to-treat principle was implemented, how compliance with study medication and completeness of follow-up was achieved, how double blinding was maintained throughout the study structure, and how patient safety was protected. The protocol ruled out participation in any other study at the same time by ACTION participants. Our experience showed that the reasons for this are not always understood by investigators. Unequivocal operational definitions of the procedural concepts that characterize randomized clinical trials should not only be the basis of QM, but also of reporting results.