Women with epilepsy are more likely to have menstrual disorders than women in the general population. Estimates vary because of different definitions of menstrual disorder. Our best estimate is that perhaps one of every three women with epilepsy may be affected compared with one of seven in the general population. Menstrual disorders are significant because they are associated with anovulatory cycles that may increase the risks for infertility, migraine, emotional disorders, and female cancers. They are neurologically important because they are associated with greater seizure frequency. Increasing evidence implicates both epilepsy itself and antiepileptic drug (AED) use as causal or contributory factors. These factors can alter reproductive hormone levels and promote the development of reproductive endocrine disorders, especially polycystic ovarian syndrome (PCOS). Among AEDs, valproate has been associated with the development of characteristic PCOS features. The risk appears to be particularly high when valproate use is started in childhood or adolescence. Menopause tends to occur earlier in women with epilepsy, especially in the setting of a high lifetime number of seizures and lifetime use of multiple enzyme-inducing AEDs. The intricate relationship between reproductive disorders and epilepsy suggests that reproductive function should be monitored closely as part of the comprehensive care of women with epilepsy.