The efficacy of chronic oral treatment with a total daily dose of 320 mg sotalol, given as a single or as two divided doses, was compared with placebo in a double-blind cross-over study of 12 patients with angina pectoris. Sotalol given once or twice daily significantly reduced heart rate and systolic and diastolic blood pressures at rest. The exercise heart rates were significantly decreased in both treatment groups. After sotalol 320 mg once daily, there was a greater reduction in the maximum exercise heart rate 2 h after taking the last tablet than after sotalol 160 mg b.i.d. The systolic blood pressure at the highest comparable work-load was significantly and equally reduced by sotalol both once and twice daily. Total work (watts X minutes in both sotalol treatment groups was significantly increased compared to placebo. There was no difference between the two sotalol dosage regimens. The peak plasma levels were higher after the once daily treatment, but the trough levels were similar for both regimens. No serious side effects were observed.