Bevantolol is a novel beta 1-selective beta-adrenoceptor antagonist. The Study Group evaluated its therapeutic utility (100-300 mg bid) compared with propranolol (80-240 mg bid) in 266 patients with mild to moderate essential hypertension (WHO Grades I and II, sitting diastolic blood pressure (DBP) greater than or equal to 95 mmHg). There was no difference in their antihypertensive efficacy over six months, 77% being controlled (DBP less than or equal to 90 mmHg) on bevantolol and 81% on propranolol. Hydrochlorothiazide 25-50 mg bid added later improved BP control in those incompletely controlled on bevantolol monotherapy. Both beta-adrenoceptor antagonists also reduced intraocular pressure. Bevantolol caused significantly fewer adverse effects than propranolol with many fewer withdrawals during long-term therapy. This unique clinical pharmacologic profile of bevantolol enhances its therapeutic usefulness and may relate to alpha-adrenoceptor antagonist activity, as well as to its beta 1-selectivity.