Objective: To compare sexual function and reproductive hormone levels among men with epilepsy who took various antiepileptic drugs (AEDs), untreated men with epilepsy, and normal controls. Methods: Subjects were 85 men with localization-related epilepsy (25 on carbamazepine [CBZ], 25 on phenytoin [PHT], 25 on lamotr igine [LTG], and 10 untreated for at least 6 months [no AED]) and 25 controls. Sexual function scores (S-scores), hormone levels (bioactive testosterone, estradiol), hormone ratios (bioactive testosterone/bioactive estradiol), and gonadal efficiency (bioactive testosterone/luteinizing hormone) were compared among the five groups. Results: S-scores, bioactive testosterone levels, bioactive testosterone/bioactive estradiol, and bioactive testos-terone/luteinizing hormone were significantly greater in the control and LTG groups than in the CBZ and PHT groups. Sex hormone binding globulin was significantly higher in the CBZ and PHT groups than in all other groups. S-scores were below the control range in 20%of the men with epilepsy, including 32.0%on CBZ, 24%on PHT, 20%on no AEDs, and 4%on LTG (χ2: p = 0.08 for all four groups; χ2: p = 0.02 for the three AED groups). Bioactive testosterone was below the control range in 28.2%, including 48%on CBZ, 28%on PHT, 20%on no AEDs, and 12%on LTG (χ2: p = 0.02). Among men with epilepsy who had low S-scores, 70.6%had bioactive testosterone levels below the control range as compared to 17.6%among men with normal S-scores (χ2:p < 0.0001). Among men with epilepsy who had abnormally low bioactive testoste rone, 50.0%had low S-scores; among men with normal bioactive testosterone, 8.2 %had low S-scores (χ2:p < 0.0001). Bioactive testosterone decline with age wa s significantly greater among men with epilepsy than among controls and notably greater in the CBZ and PHT groups than in the LTG and untreated groups. Conclusi ons: Sexual function, bioavailable testosterone levels, and gonadal efficiency i n men with epilepsy who took lamotrigine were comparable to control and untreate d values and significantly greater than with carbamazepine or phenytoin treatmen t. Objective: To compare sexual function and reproductive hormone levels among men with epilepsy who took various antiepileptic drugs (AEDs), untreated men with epilepsy, and normal controls. Methods: Subjects were 85 men with localization-related epilepsy (25 on carbamazepine [CBZ] , 25 on phenytoin [PHT], 25 on lamotrigine [LTG], and 10 untreated for at least 6 months [no AED]) and 25 controls. Sexual function scores (S-scores), hormone levels (bioactive testosterone, estradiol) , bioactivity testosterone / bioactive estradiol, and gonadal efficiency (bioactive testosterone / luteinizing hormone) were among the five groups. Results: S-scores, bioactive testosterone levels, bioactive testosterone / bioactive estradiol, and bioactive testos- terone / Luteinizing hormone were significantly greater in the control and LTG groups than in the CBZ and PHT groups. Sex hormone binding globulin was significantly higher in the CBZ and PHT groups than in all other groups. S-scores were below the control range in 20% of the men with epilepsy, including 32.0% on CBZ, 24% on PHT, 20% on no AEDs, and 4% on LTG (χ2: p = 0.08 for all four groups; 0.02 for the three AED groups. Bioactive testosterone was below the control range in 28.2%, including 48% on CBZ, 28% on PHT, 20% on no AEDs, and 12% on LTG (χ2: p = 0.02) men with epilepsy who had low S-scores, 70.6% had bioactive testosterone levels below the control range as compared to 17.6% among men with normal S-scores (χ2: p <0.0001). Among men with epilepsy who had abnormally low bioactive testoste rone, 50.0% had low S-scores; among men with normal bioactive testosterone, 8.2% had low S-scores (χ2: p <0.0001). Bioactive testosterone decline with age was significantly greater among men with epilepsy than among controls and notably greater in the CBZ and PHT groups than in the LTG and untreated groups. Conclusi ons: Sexual function, bioavailable testosterone levels, and gonadal efficiency in men with epilepsy w ho took lamotrigine were comparable to control and untreated values ​​and significantly greater than with carbamazepine or phenytoin treatment.