We looked retrospectively for all cases of toxic epidermal necrolysis that occurred in France over a 5-year period to appreciate the incidence of this disorder and its drug etiology. Of the 399 cases identified, we obtained detailed information on 344 cases and validated 253 cases. From response rates (66% to 98%), we estimated the actual total number of cases to be 333, and the incidence of toxic epidermal necrolysis in France to 1.2 cases per million per year. An independent estimation derived from death certificates gave a figure of 1.3 cases per million per year. When the number of cases with a given drug present were related to the defined daily doses of that drug sold over the 5-year period, the highest ratios were for sulfadiazin (230.10(-8], isoxica (41.10(-8], oxyphenbutazone (18.10(-8], phenytoin (14.10(-8], fenbufen (13.10(-8], and cotrimoxazole (12.10(-8]. This first nationwide study confirmed the rarity of toxic epidermal necrolysis. Within the two main classes of responsible drugs (antibacterial sulfonamides and nonsteroidal anti-inflammatory agents) the risks linked to different drugs appeared quite different, even for closely chemically related products.