BACKGROUND: Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) are rare but life-threatening disorders characterized by widespread epidermal necrosis of the skin and mucosa. The severity-of-illness scoring system for TEN (SCORTEN) was widely used since 2000 as a standard prognostic tool consisting of seven clinical values. METHODS: To evaluate the prognosis using current treatments and risk factors for mortality, we retrospectively analyzed 59 cases of TEN, including SJS/TEN overlap treated in two university hospitals from January 2000 to March 2020. RESULTS: The mortality rate of TEN was 13.6% (8/59). All patients treated with high-dose steroid administration in combination with plasma exchange and/or immunoglobulin therapy recovered. Logistic regression analysis showed nine clinical composite scores, namely: heart rate (≧120 bpm), malignancy present, percentage of body surface area with epidermal detachment (>10%), blood urea nitrogen (>28 mg/dL), serum bicarbonate level (<20 mEq/L), serum glucose level (>252 mg/dL), age (≧71 years), the interval between disease onset and treatment initiation at the specialty hospital (≧8 days), and respiratory disorder within 48 h after admission. The receiver operating characteristic curves confirmed a high potential for predicting the prognosis of TEN. CONCLUSIONS: Recent developments in treatment strategies have contributed to the improved prognosis of TEN patients. A modified severity scoring model composed of nine scores may be helpful in the prediction of TEN prognosis in recent patients. Further large-scale studies are needed to confirm mortality findings to improve prognostication in patients with TEN.