To assess the effects of current treatments with β-blockers or calcium antagonists on the clinical outcome of acute myocardial infarction (MI), enzymatically estimated infarct sizes, circulatory arrests from ventricular tachyarrhythmias, ventricular tachycardia (VT)/ventricular fibrillation (VF), and in-hospital mortality were analyzed retrospectively from 7,922 citizens of Malmö, Sweden, hospitalized due to a first MI between 1973 and 1987. Of these patients, 296 were on treatment with calcium antagonists, 393 on treatment with a β<sub>1</sub>-selective β-blocker, 482 with a nonselec-tive β-blocker, and 95 on combined treatment with β-blockers and calcium antagonists at the time of admission to hospital. In a set of multivariate analyses including several clinical characteristics, patients on treatment with a nonselective β-blocker had a significantly lower peak aspartate ami-notransferase (ASAT; difference -0.70 µkat/1, 95% CL: -1.24 to -0.16), whereas no significant relations between peak ASAT and treatment with cardioselective β-blockers or calcium antagonists were found. Treatment with cardioselective β-blockers or calcium antagonists, in contrast to treatment with a nonselective β-blocker, were significant predictors of the occurrence of circulatory arrests from VT/VF. The relative risk of VT/VF in patients on cardioselective β-blockers was 1.51 (95% CI: 1.12-2.03), and in patients on calcium antagonists 1.44 (95% CI: 1.03-2.02). None of the treatments were significantly associated with in-hospital mortality. In patients on β-blockers or calcium antagonists when suffering their first MI, nonselective β-blockade may reduce infarct size. Treatment with β-block-ers or calcium antagonists identified patients with an increased risk of circulatory arrests from VT/VF, but neither of the treatments were significantly associated with in-hospital mortality. We suggest that only minor differences exist between the effects of chronic treatment with β-blockers and calcium antagonists on the outcome of an acute MI.