From 3.457 epileptic patients, 1.574 females from 12 to 50 years old, considered probably in ovulatory age, were studied regarding the influence of menstruation upon epileptic fits. The females were compared with a group of epilepsies in general and with a group of male epileptic patients (476 cases) of same age exhibiting monthly seizures, a rhythm similar to the menstrual cycle in woman. The results led the author to the following conclusions: 1) In 353 epileptic females (22,4%) the epilepsy was influenced by the menstruation. 2) The exacerbation of fits predominate in the premenstrual and menstrual periods. 3) No significant differences was observed when compared females in ovulatory age exhibiting monthly seizures (14%) with male of similar age and similar frequency of seizures (16%); this fact is against the correlation between the cyclical events represented by epileptic fits and menstruation. 4) Focal non-temporal abnormalities predominate in the females that was influenced by menstruation.