Long-term preventive effects of standard statin therapy in patients with acute myocardial infarction (AMI) against a secondary cardiac event remain unclear. The aims of this study were to evaluate and clarify characteristics of patients with AMI in whom standard statin therapy has beneficial effects against a secondary event in a real-world setting. Between 1999 and 2004, 4,075 patients with AMI were registered and followed prospectively, of whom 1,404 (matched by propensity scores) were analyzed. Statin use was defined as prescription on discharge from the hospital, and the control group was not prescribed statins at discharge. The primary end point was total mortality rate. Final follow-up was performed in June 2006 (median 4.1 years), and follow-up rate was 97.2%. During follow-up, 139 patients died, including 87 (12.4%) from the control group and 52 (7.4%) from the statin group. The hazard ratio for statin therapy was 0.64 (95% confidence interval 0.45 to 0.90, p = 0.011) throughout the study. Early statin therapy was strongly correlated with a lower risk of cardiovascular death, less recurrence of AMI, and less heart failure. Statin therapy was particularly beneficial for men, patients > or =60 years of age, and patients with a high low-density lipoprotein cholesterol level > or =155 mg/dl. In conclusion, these findings suggest that initiating standard rather than intensive statin therapy immediately after AMI decreases long-term mortality and subsequent cardiac events.