Objectives. This is an initial pilot study to acquire information upon which a more specific, statistically rigorous follow-on investigation will be based. The objectives of the overall project are: (1) to compare the absolute levels and rates of change in levels of gonadal and neuroactive steroids in women with complex partial seizures and catamenial epilepsy with those of women with non-catamenial epilepsy and women volunteers without epilepsy, and (2) to determine if fluctuations in the levels of gonadal hormones (estrone, estradiol, progesterone) and neuroactive steroids (allopregnanolone, pregnenolone and dehydroepiandrosterone) correlate with seizure occurrence and the frequency of interictal spikes/wave discharges in women with catamenial seizure exacerbations.