Tolamolol is a phenoxypropranolamine derivative that preferentially inhibits myocardial beta adrenoreceptors, possesses beta blocking potency equivalent to propranolol, has little or no direct cell membrane effect and lacks beta adrenergic stimulating action. Cardioselective beta adrenergic blockade with tolamolol was highly effective in controlling ventricular rate in supraventricular arrhythmias and reduced the frequency of ventricular ectopic beats in half of the small group of patients with this arrhythmia. It is particularly applicable in patients with obstructive pulmonary disease in whom cardiac beta adrenergic blockade is indicated. Hypotension is an important potential side effect. Tolamolol and propranolol are equal in anti-anginal efficacy but tolamolol has the advantage of being cardioselective. It is superior to practolol. Tolamolol had no effect on sperm motility.