Verapamil, a calcium antagonist, was compared with propranolol, a widely used beta-adrenoreceptor blocker, in hypertensive patients with respect to its antihypertensive efficacy and incidence and severity of adverse effects. Both drugs caused similar blood pressure reductions without interfering with pulse pressure. The hypotensive effect of verapamil was not accompanied by any effect on heart rate, while after propranolol there was a significant bradycardia. ST-segment and T wave abnormalities at rest and after exercise were partially or completely reverted by both drugs. The incidence and severity of adverse effects was very low and no patient was withdrawn from the study because of complaints due to the active drugs. Verapamil can be compared as antihypertensive drug to the beta-blocker propranolol and this may justify, together with the absence of negative effects on lipids, blood sugar, serum electrolytes and renal function, its use as an antihypertensive drug of first choice.