The relationships between seizures in epileptic women and the hormones estrogen and progesterone are under increasing study. Serum concentrations of estrogen and progesterone parallel cerebrospinal concentrations, and circulating sex hormones are concentrated in specific areas of the brain that regulate sexual behavior. These centers include two potentially epileptogenic regions--the amygdala and hippocampus. Many of these structures are physiologically affected in vitro by estrogen and progesterone. Exogenous sex hormones change the seizure threshold in animal models of epilepsy. Cyclical hormonal variations may influence electroencephalographic activity and affect seizure frequency in women with epilepsy. Hormonal therapy may be appropriate adjunctive anticonvulsant treatment, particularly for women with seizures that are catamenial or associated with a menstrual or reproductive endocrine disorder.