This analysis was carried out to clarify the capacity of metoprolol to prevent cardiac events in Japanese post-myocardial infarction patients during a follow-up period of 16.3 months. Cardiac events occurred in 44 of 650 patients treated without beta-blockers (6.8%) and in 13 of 432 patients treated with metoprolol (3.0%), which represents a significant decline in the incidence of cardiac events among patients receiving metoprolol (p<0.01, odds ratio 0.43, 95% confidence interval 0.23-0.80). Because this was a retrospective analysis, there were unavoidable differences in the backgrounds of the patients in the 2 groups. Subgroup analyses, each focusing on a specific patient characteristic, were therefore performed. These showed that metoprolol effectively reduced cardiac events in many subgroups. Furthermore, multivariate analysis carried out to exclude any modification based on the differences in patient background confirmed metoprolol to be effective in reducing subsequent cardiac events in post-myocardial infarction patients. A large, randomized, placebo-controlled clinical trial needs to be performed in the Japanese population to confirm the present result.