Sympathetic dysfunction is often present in migraine. It has been suggested that serum dopamine-beta-hydroxylase (D beta H) can be taken as an index of peripheral sympathetic activity. We studied the serum D beta H activity in migraine with and without aura and in tension-type headache patients compared with healthy control subjects. The serum D beta H activity was significantly lower in migraine and tension-type headache patients than in the control group. No significant difference was observed among the three groups of patients studied. These findings suggest that patients with migraine and tension-type headache have a sympathetic hypofunction that may play an important role in the pathogenesis.