Catamenial epilepsy (CE) is characterized by epileptic seizures in the female occurring rhythmatically with the menstrual cycle. Hormonal mechanisms have been proposed as a cause of this epileptic form. Few reports about the efficacy of anti-epileptic drugs (AEDs) have been published. We studied prospectively women with CE who were treated with lamotrigine (LTG) for a period of 3 months in order to evaluate its efficacy, measuring the progesterone levels before and after LTG at the same time. LTG seemed to be efficacious in 66% of women, meaning the disappearance of seizures or reduction of 50% or more of the number of seizures. The reported side effects were few and mild, and the drug was well tolerated. Serum progesterone levels were found to rise during LTG treatment.