The purpose of the present study was the evaluation of the excitability threshold and the central motor conduction time (CCT) studied by means of electromagnetic cortical stimulation in ten subjects affected by menstrual migraine without aura, both in the ictal and the interictal period. The patients were chosen from among a group of 254 outpatients affected by migraine, diagnosed according to the International Headache Society criteria. The control group consisted of ten healthy female subjects. As far as CCTs were concerned no differences emerged between patients and controls. However in the patient group we found a significant increase in the excitability threshold values, both in the ictal and the interictal period, and in both hemispheres. If confirmed, the increased excitability threshold may be a useful neurophysiological correlate of migraine without aura.