It has been suggested that magnesium plays a central role in different etiopathogenetic conditions involved in the onset of migraine. We measured, by atomic absorption spectrophotometry, serum and salivary magnesium levels in drug-free migraine patients with and without aura and in tension-type headache patients. Migraine sufferers with and without aura and tension-type headache had significantly lower levels of serum and salivary magnesium concentrations in the interical periods than a group of healthy young individuals. Serum magnesium levels tended to be further reduced during attacks in all patient groups studied. A statistically significant decrease in salivary magnesium levels was evident only for migraine patients with aura. Serum magnesium levels and to a lesser extent salivary magnesium levels might express indirectly the lowering of brain extracellular magnesium concentration which occurs in migraine patients both in the intererictal periods and ictally.