Although propranolol is still the drug of first choice for migraine prophylaxis, the optimal antimigraine dose of this drug is still unknown. The main aim of our study is to clarify this point. Fifty-three patients suffering from severe migraine attacks were given propranolol at low doses, close to or up to 1 mg/kg body weight daily, for one month. If the patient responded, then treatment was maintained unchanged for a further two months. If the patient did not respond, propranolol was progressively increased until control was obtained. Thirty-nine (73.5%) patients responded to low doses, and 7 of the 17 patients whose dose had been increased, because of poor or absent response, showed improvement. Five patients did not finish the study because of intolerable side effects, which intensified as the dose was increased. Tolerance was not noticed. In addition to confirming the well-known utility of propranolol in migraine prophylaxis, our results show that low doses are effective in controlling serious migraine bouts in many patients. Fewer than a third of patients will need higher doses in controlling migraine attacks.