Bunolol is non-selective beta-adrenoreceptor antagonist with significant antihypertensive, antiarrhythmic and local anesthetic activities. Bunolol is a racemic mixture and Levobunolol is greater than 60 times more potent than its dextro isomer in its beta-blocking activity. Bunolol is 3 times as potent as propranolol by i.v. administration in anesthetized dogs in antagonizing the cardiovascular actions of isoproterenol and the response to cardioaccelerans nerve stimulation. When oral doses were given to unanesthetized dogs with subsequent induction of anesthesia, Bunolol was 20 times as potent as propranolol. The β-adrenergic blocking activity of Bunolol appeared to be competitive, and the activity was largely restricted to the l-isomer. Bunolol is extensively metabolized by both oxidative and reductive routes.