We retrospectively investigated 132 patients with Stevens-Johnson syndrome (SJS) and toxic epidermal necrolysis (TEN) treated at two university hospitals between January 2000 and March 2019. The mortality rates for SJS and TEN were 1.3% and 12.5%, respectively. Interestingly, over the last 7 years (between 2012 and 2019), the mortality rate for TEN was 3.8%. These results suggest that steroid administration in combination with plasma exchange and/or immunoglobulin therapy has contributed to an improved prognosis of patients with TEN. In addition to these treatments, the significantly short interval between disease onset and treatment initiation at our hospitals may have contributed to reduced mortality rates associated with TEN. This study reaffirms the importance of early diagnosis and prompt initiation of intensive medical treatment for TEN.