In a multicentre double-blind randomised study, the effect of sotalol 320 mg once daily was compared with that of placebo in patients surviving an acute myocardial infarction. Treatment was started 5--14 days after infarction in 1456 patients (60% being randomised to sotalol, and 40% to placebo) who represented 45% of those evaluated for entry. Patients were followed for 12 months. The mortality rate was 7.3% (64 patients) in the sotalol group and 8.9% (52 patients) in the placebo group. The mortality was 18% lower in the sotalol than in the placebo group, but this difference was not statistically significant. The rate of definite myocardial reinfarction was 41% lower in the sotalol group than in the placebo group (p less than 0.05). Although the differences in mortality were not significant, this trial supports the evidence that, in the year after myocardial infarction, beta adrenoceptor blocking drugs reduce mortality by 20--25%.