The efficacy and tolerance of 20 mg flunarizine i.v. were tested in comparison with placebo in a multicentre randomised double-blind trial in the acute treatment of migraine attacks. Sixty case reports were included in theevaluation; 31 patients were treated with flunarizine and 29 with placebo. Flunarizine proved to be significantly superior in its effect on the intensity of pain and the typical concomitant symptoms of the attacks. Patients were classed as responders who displayed a reduction in pain intensity by at least 50% within 60 minutes after the administration of flunarizine. 23 patients (= 74.2%) were responders, including 11 patients being without pain after60 minutes. In the placebo group the responder rate was 27.6%. The fact that both groups were comparable in all respects should be emphasized. The tolerance of intravenously administered flunarizine was excellent and corresponded to that of placebo. Apart from a sedative effect reported by 9 patients there were no side-effects. The circulatory conditions remained largely stable. The result of this study seems to indicate that an intravenous injection of 20 mg flunarizine might represent a genuine alternative, and as regards tolerance even a superior one, to the parenteral administration of ergotamine in migraine attacks.