Seventeen patients with migraine headaches, occurring at least twice a month, were successfully treated with an ACE inhibitor for prophylaxis. Most were given enalapril, some used lisinopril. Duration of treatment ranged from 3 months to 3 years. Side effects were generally not noted. Cough occurred in four patients. The mechanism of action is unknown. The lack of side effects and the presence of clearly sustained benefit in this small group of migraineurs should prompt further study and use of this class of drugs for prophylaxis.