The effects of bufuralol and its carbinol metabolite were compared with those of propranolol in the anesthetized and conscious cat and dog. Bufuralol and its carbinol metabolite are nonselective .beta.-adrenoceptor antagonists; the former has equivalent potency to propranolol, whereas the latter is 6 times more potent. In anesthetized animals both bufuralol and its metabolite exhibited partial agonistic activity, resulting in tachycardia and vasodilation. In conscious cats there was no change in heart rate or slight bradycardia, whereas in dogs both compounds again produced tachycardia. In anesthetized and conscious cats and conscious dogs, both bufuralol and the metabolite increased abdominal aortic blood flow. There was a reduction in blood pressure in the conscious dog. Evidently, partial agonistic activity of bufuralol and its carbinol metabolite is exerted mainly at the .beta.2-adrenoceptor, producing vasodilation and reducing peripheral resistance, resulting in a reduction in blood pressure with a long duration of action.