This paper reports the results of a 12-month prospective follow-up study on the effects of carbamazepine (CBZ) medication on serum sex and pituitary hormone concentrations in 21 male patients with recently diagnosed epilepsy. The results of the present study indicate that a change occurs in the androgen balance during CBZ medication in male patients with epilepsy: a rise in serum sex hormone binding globulin levels results in decreased free androgen index values, and dehydroepiandrosterone sulfate serum levels decrease. Serum testosterone and free testosterone levels remain unchanged, but estradiol levels decrease. Serum basal prolactin (PRL) levels remain unchanged, but the PRL responses to thyrotropin-releasing hormone and metoclopramide increase slightly during the first year of CBZ medication. Basal and stimulated serum gonadotropin levels remain unchanged. The clinical consequences of these hormonal changes during CBZ medication call for further studies.