Eighty-seven patients with toxic epidermal necrolysis were observed at Hôpital Henri Mondor in Créteil, France, over the last 12 years. The mean percentage of body surface area involved was 39%. Erosive mucous membrane lesions, identical to those of Stevens-Johnson syndrome, were present in all but three cases. Necrolysis was sometimes generalized within 24 hours but usually spread progressively after a Stevens-Johnson syndrome-like aspect at the onset. Mortality was 25%. Infection, mainly with Staphylococus aureus and Pseudomonas aeruginosa, was the first cause of death, clearly responsible in ten of 20 cases. Age, extension of necrolysis, idiopathic nature of toxic epidermal necrolysis, ingestion of many drugs, elevation of urea, creatinine, and glucose levels, neutropenia, lymphopenia, and thrombocytopenia were statistically linked to a bad prognosis. A multivariant analysis showed that three of these prognosis factors are of paramount importance, namely: age, area of necrolysis, and serum urea level. Pigmentary changes and sicca syndrome were frequently observed sequelae in survivors.