Toxic epidermal necrolysis is a rare clinical picture generally caused by drugs and rarely by infectious agents and is characterized by peeling of the epidermis of the skin. It is associated with high mortality and morbidity and the treatment is still controversial. In this case report, we present a 13-year-old girl who developed toxic epidermal necrolysis due to trimethoprim-sulfamethoxazole (TMP-SMX) treatment for urinary tract infection. She had developed fever and skin lesions on the seventh day of (TMP-SMX) treatment. Her skin lesions progressed and alere diagnosed as toxic epidermal necrolysis and she did not show any improvement with supportive therapy. Her lesions responded to intravenous immunoglobulin (IVIG) 400 mg/kg/day for five consecutive days given on the fourth day. In conclusion, we want to highlight by means of this case, this rare adverse effect of TMP-SMX and the importance of IVIG as an alternative choice of treatment for toxic epidermal necrolysis patients. Anahtar Kelimeler : Toksik epidermal nekrolizis, trimetoprim-sulfametaksazol, istenmeyen etki, intravenöz immünglobülin, Toxic epidermal necrolysis, trimethoprim-sulfamethoxazole, adverse event, intravenous immunoglobulin