Carbamazepine--widely used in the treatment of trigeminal neuralgia, seizure disorders, and more recently, manic-depressive illness--is generally safe and well tolerated. Although serious adverse reactions, such as hematologic toxicity, may occur rarely, we have found that carbamazepine-induced rash is common, occurring in 13 (12%) of 113 patients. We describe our experience with carbamazepine-induced rash, including clinical characteristics, demographic features, and associated laboratory findings. Integrating our findings with the literature, we also discuss incidence, possible mechanisms, and implications for treatment because these benign rashes can occasionally progress to more fulminant and life-threatening eruptions.