Objectives: To investigate the epidemiologic features of Lyell syndrome (TEN syndrome) at the National hospital of Dermatology and Venereology (NHDV) from January 1, 2007 to December 31,2010. Materials and methods: a cross - sectional study based on data of 39 patients with Lyell syndrome hospitalized at the NHDV. Results: During 4 years, there were 39 patients with Lyell syndrome, accounting for 1.15 percent of patients suffered from toxidermie at the NHDV. There were 26 females (66.67 percent) and 13 males (33.33 percent) in the age range of 10 months - 86 years (mean age 46.8 + or - 18.8 years). Thirty six patients (92.31 percent) had no allergy history. Twenty patients (51.28 percent) were farmers. Investigation of medicine related to Lyell syndrom showing that nineteen patients (48.72 percent) using the traditional medicine. Two cases (5.14 percent) were involved in traditional medicine with NSAIDs. Taking tegretol was noted in 3 patients (7.70 percent), NSAIDs in 2 patients (5.14 percent), allopurinol in one patient (2.56 percent) and sabutamol in one pateint (2.56 percent). Conclusion: Lyell syndrome accounts for 1.15 percent of patients with toxidermie at the NHDV. Women are affected more often than men. There was 92.31 percent of patients with the Lyell syndrom as the first time of drug allergy, and 53.68 percent of cases involving in using the traditional medicine.