Toxic epidermal necrolysis is a rare but often fatal hypersensitivity reaction to numerous agents, including most anticonvulsants. The authors present a case of fatal phenytoin-related toxic epidermal necrolysis in a patient who was given prophylactic anticonvulsant therapy after he sustained a moderately severe closed head injury. The typical course and current management of toxic epidermal necrolysis are reviewed, as are the indications for the prophylaxis of posttraumatic epilepsy.