Anticonvulsant hypersensitivity syndrome is a severe, potentially life-threatening, reaction to the aromatic anticonvulsant medications. Reported here is a case of anticonvulsant hypersensitivity syndrome secondary to phenobarbital in a 2-year-old boy; he responded to drug withdrawal, corticosteroids, and intravenous immunoglobulin. The literature regarding treatment of this syndrome is reviewed.