In women with epilepsy, seizures can be influenced by variations in sex hormone secretion during the menstrual cycle. The proconvulsant effects of estrogen have been demonstrated in both animals and humans, whereas progesterone has been found to have anticonvulsant properties. Catamenial epilepsy affects approximately one-third of women with epilepsy. This type of epilepsy has generally been defined as an increase in seizure frequency beginning immediately before or during menses. However, three distinct patterns of catamenial epilepsy have been described: perimenstrual, periovulatory, and luteal. The diagnosis of catamenial epilepsy can be made through careful assessment of menstrual and seizure diaries and characterization of cycle type and duration. A variety of therapies for catamenial epilepsy have been proposed, including acetazolamide, cyclical use of benzodiazepines or conventional antiepileptic drugs (AEDs), and hormonal therapy. However, evidence for the effectiveness of these treatment approaches comes from small, unblinded series or anecdotal reports. Larger multicenter trials, as well as further investigation of the pathophysiology of the disorder, are needed to identify the most effective treatment for women with catamenial epilepsy.