The objective of the study was to investigate the efficacy of different dose levels of bopindolol monotherapy in hypertension. This potent nonselective beta-adrenergic receptor blocker has intrinsic sympathomimetic activity and long duration of action. Forty-four patients with essential hypertension of mild (n = 40) or moderate (n = 4) severity (90 less than DBP less than or equal to 115 mmHg at the end of the placebo period) entered and completed the single-blind, placebo-controlled trial. The study lasted 14 weeks: 2 weeks on placebo, and 12 weeks on active treatment during which the initial dose of bopindolol, 1 mg daily, was augmented up to 1.5 mg, then to 2 mg at four-week intervals until BP normalized or a maximum dose of 2 mg/day bopindolol was reached. The bopindolol was administered once a day in the morning. Patients were seen every other week in the morning before drug taking, when BP and heart rate, supine and standing, a twelve lead ECG and side-effects were recorded. Compared with placebo, supine BP was significantly reduced by bopindolol: from 169 +/- 2/103 +/- 1 mmHg to 148 +/- 3/92 +/- 1, 144 +/- 3/90 +/- 1 and 136 +/- 2/85 +/- 0.6 mmHg at the end of 4, 8 and 12 weeks of treatments, respectively (P less than 0.01 for each). BP changes during standing were similar. Bopindolol lowered the supine heart rate from 84 +/- 2 to 75 +/- 1, 74 +/- 1, 72 +/- 1 beats/min (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)