We evaluated telmisartan 80 mg for migraine prophylaxis. Migraine patients (n = 95) with three to seven migraine attacks in 3 months were randomized, double-blind to telmisartan or placebo. The primary end-point was the reduction in the number of migraine days (i.e. a day with > or = 1 h of symptoms) between the 4-week baseline period and the last 4 weeks of the 12-week treatment period. A responder was recorded when there was a symptom reduction of > or = 50% in these 4-week baseline and treatment periods. The reduction in migraine days was 1.65 with telmisartan and 1.14 with placebo (P > 0.05). Post hoc analyses adjusting for baseline and centre showed a 38% reduction in migraine days with telmisartan vs. 15% with placebo (P = 0.03), and a borderline significant difference in responders (40% vs. 25%, P = 0.07). The incidence of adverse events was similar between treatments. This study indicates that telmisartan might be effective in migraine prophylaxis.