PUPOSE: Little is known about the advantages and disadvantages of participation in a clinical trial for patients with coronary heart disease. We hypothesized that participation itself in a long-term clinical trial with regular clinical evaluation and adjustment of treatments might lead to survival gain among patients with coronary artery disease who agreed or refused to participate in the Bezafibrate Infarction Prevention study. SUBJECTS AND METHODS: The study was performed in 18 university hospitals. There were 3502 patients who fulfilled the inclusion criteria. Among them, 3122 patients signed informed consent and were included in the study ("participants"), whereas 380 declined to participate ("nonparticipants"). For all participants, routine visits to the clinics were scheduled bimonthly for study medication distribution and compliance assessment, and every 4 months for clinical evaluation and management. Nonparticipants continued with community-based treatment and were followed only for mortality. RESULTS: The two groups were similar with regard to age, sex, and the prevalence of most cardiovascular diseases, risk factors, and medications, except that participants were more likely to have presented with an anginal syndrome (1788 [57%] vs. 190 [50%]) and to have symptomatic heart failure (754 [25%] vs. 66 [18%]). During follow-up (mean [± SD], 7.7 ± 0.8 years), 475 patients died. All-cause mortality was similar in participants (n = 423 [13.6%]) and nonparticipants (n = 52 [13.7%]). In a multivariate analysis, participation in the clinical trial was not associated with all-cause mortality (hazard ratio [HR] = 0.96; 95% confidence interval [CI]: 0.70 to 1.30) or cardiac mortality (HR = 1.12; 95% CI: 0.72 to 1.74). CONCLUSION: Participation in a long-term clinical trial in a country with readily accessible community-based medicine may not lead to survival gain in patients with coronary artery disease.