In a randomized, blind trial, enalapril and captopril were compared in 479 patients with essential hypertension. The results showed that both enalapril and captopril had similar effects on the blood pressure. The response rate was 77.8% with enalapril and 70.4% with captopril. Blood pressure lowered 2.68/1.59 kPa (20.1/11.9 mmHg) in enalapril group versus 2.44/1.43 kPa (18.3/10.7 mmHg) in captopril group. No serious side effects were observed and both enalapril and captopril were well tolerated. Thus, enalapril and captopril appear equally effective and safe in patients with essential hypertension and enalapril is better accepted by patients because of its longer duration of antihypertensive activity.