In a double-blind randomized study of 154 postmyocardial infarction patients assigned to metoprolol (100 mg twice daily) and 147 patients assigned placebo, the outcome during a 3-year follow-up according to serum cholesterol concentrations was evaluated. There was no indication that metoprolol influenced the total serum cholesterol concentration. The median cholesterol value at 3 months was 6.7 mmol/l. In patients with cholesterol >6.7 mmol/l, nonfatal reinfarctions were reduced in the metoprolol group (7 vs. 24%; p < 0.01). In patients with cholesterol > 6.7 mmol/l, mortality was lower in those treated with metoprolol (8 vs. 20%; p < 0.05). The beneficial effect of conventional postinfarction beta-blockade with metoprolol is independent of serum cholesterol concentration.