Propranolol is an established agent in migraine prophylaxis. Uncontrolled studies have suggested an action in the acute attack. We present the first double-blind placebo controlled study of propranolol in 27 unselected patients with common (migraine without aura) and classical (migraine with aura) migraine. There were 23 pairs of headaches in the 14 patients who completed the study. No difference was found, when the data were analysed by headache pair or by patient, in severity duration and subjective assessment of efficacy between those treated in an attack with propranolol 40 mg and placebo.