We describe a patient with Kleine-Levin syndrome who was initially misdiagnosed as having epilepsy and who achieved complete remission on carbamazepine treatment. A drug effect was established when symptoms recurred after carbamazepine taper and disappeared after reintroduction of the drug. Carbamazepine, a safer drug than lithium, can be a highly effective treatment in some patients with Kleine-Levin syndrome. This syndrome can sometimes be confused with epilepsy because of the episodic nature of the symptoms and the occasional response to anticonvulsants.