Dihydroergokryptine has been evaluated in the prophylaxis of headache attacks in patients with migraine without aura. The study was controlled vs dihydroergotamine with a double-blind crossover design. After a 1-month run-in period, 30 patients were randomized into two groups and submitted to 4 months treatment with dihydroergokryptine 10 mg b.i.d. or dihydroergotamine (controlled release) 5 mg b.i.d. The treatment was repeated in crossover after 2 months washout. The clinical patients' evaluation was determined by monthly Pain Total Index recording, headache days/month and analgesic consumption. The patients were considered responsible when Pain Total Index decreased by 50% or more in 1 or more months of each treatment period; otherwise the patients were considered unresponsive. The response rate to dihydroergokryptine was 66% while 48% of cases were responsive to dihydroergotamine. The response rate to both treatments was 41%, while 26% did not respond to either treatment. Seven cases unresponsive to dihydroergotamine responded positively to dihydroergokryptine while two cases only, resistant to dihydroergokryptine, responded positively to dihydroergotamine. Three cases dropped out during treatment with dihydroergotamine due to gastric pain and nausea, while they did not show any side effects during dihydroergokryptine therapy. During treatment with dihydroergokryptine there was one case of skin rash which disappeared after drug withdrawal. In conclusion, dihydroergokryptine appears to be an effective drug for the prophylaxis of migraine attacks.