SummaryVasculitis can be a systemic manifestation of hypersensitivity to many drugs, among them anticonvulsants. The clinical manifestations include rash and renal, hepatic, and pulmonary involvement. Diagnosis is based upon clinical findings and a characteristic biopsy showing granulocytic and sometimes eosinophilic infiltrates around small blood vessels, especially venules. A severe form of hypersensitivity vasculitis, with extensive visceral involvement and poor prognosis, has been encountered very rarely following phenytoin and in isolated cases following carbamazepine and trimethadione administration. Drug-induced systemic lupus erythematosus is much more frequent, with distinct clinical and laboratory abnormalities. The syndrome was described following treatment with most anticonvulsants in clinical use—phenytoin, carbamazepine, ethosuximide, trimethadione, primidone, and valproate, but not phenobarbital or benzodiazepines. The early recognition of these syndromes as being related to drugs is important, because they usually remit upon withdrawal of the offending agent.