In a double-blind controlled trial 22 patients with mild or moderate essential hypertension were treated with nicardipine 30 mg t.d.s. and 19 patients with propranolol 80 mg t.d.s. as monotherapy for 24 weeks. Blood pressure in both groups at the end of trial was equally and significantly reduced; systolic pressure 22.2 mmHg and diastolic pressure 15.5 mmHg in the supine position, and 24.4 mmHg and 18.4 mmHg, respectively, in the standing position in those on nicardipine, and by 23.7 and 16.2 mmHg and 28.0 and 19.2 mmHg, respectively, in the propranolol group. There was an initial increase in heart rate in the nicardipine group, but the rise was only moderate (3 beats/min supine p = 0.3219, and 7 beats/min standing, p = 0.0203) at the end of the 24 weeks. In the propranolol group heart rate was reduced markedly. Adverse effects occurred in 77% of patients on nicardipine and in 63% of those on propranolol, and there were no unexpected findings. The effects were mild in both groups and did not lead any patient to stop medication. One patient on propranolol was withdrawn from the trial because of poor blood pressure control and suspected angina pectoris after 5 weeks on active medication. There were no significant changes in blood chemistry, including lipoprotein classes. Overall, in comparison with propranolol, nicardipine was effective, well-tolerated and safe to use in the monotherapy of mild or moderate essential hypertension.