Headache has often been described in the hyperexcitability syndrome which recognizes an alteration of calcium and magnesium status in its etiopathogenesis. Moreover, in migraine patients magnesium has been shown to play an important role as a regulator of neuronal excitability and, therefore hypothetically, of headache. The present research involves a neurophysiological evaluation and magnesium status assessment of a group of headache patients. Nineteen patients (15 women and 4 men) with episodic tension-type headache and 30 patients (27 women and 3 men) with migraine without aura were examined. An ischemic test was carried out on the right arm with electromyographic (EMG) recording of motor unit potential activity during the interictal period. The determination of extracellular (serum and saliva) and intracellular (red and mononuclear blood cells) magnesium was also performed. The EMG test was positive in 25 of 30 migraine patients and in 2 of 19 tension-type headache patients. Between the two patient groups, there were no significant variations in the concentration of extracellular and white blood cell magnesium, while the red blood cell concentration of this mineral in the group of migraineurs was significantly reduced with respect to that in the group of tension-type headache patients (P<0.05). The positive EMG test was significantly associated with a low concentration of red blood cell magnesium (P<0.0001). These results confirm previous findings by demonstrating different etiopathogenic mechanisms as the basis of migraine and tension-type headache. Migraine seems to be related to an altered magnesium status, which manifests itself by a neuromuscular hyperexcitability and a reduced concentration in red blood cells.