We investigated the therapeutic efficacy of short-term (Asu1,7 )eel-calcitonin treatment in subjects affected by headache. All 47 patients were initially treated for 20 days intramuscularly with vehicle alone (basal values). Subsequently, they received for another 10 days a daily injection of (Asu1,7 )eel calcitonin (40 I.U. per day i.m.). The effectiveness of the treatment was evaluated in terms of changes in frequency, intensity and duration of the migraine attacks, and pain intensity and duration of daily chronic headache. The levels of plasma calcitonin, before, during and at the end of the therapy were evaluated. The clinical results show a significant difference between the observation period (vehicle alone) and the treatment phase with a significant improvement due to (Asu1,7 )eel-calcitonin treatment. In 32 patients plasma calcitonin levels were significantly modified after five days of treatment. Plasma calcium values showed no significant change.