Objective: To evaluate the lethal area 50 (LA50) and determinants of mortality in burn patients admitted to a single burn center.Methods: This retrospective cross-sectional study was conducted in a tertiary burn center affiliated with Shiraz University of Medical Sciences, Shiraz, Iran, during a 1-year period from 2015 to 2016. To determine prognostic factors in fatal burns, medical records of eligible burn patients were reviewed for demographic and clinical variables, as well as patient outcome. Also, LA50 was calculated using Probit analysis.Results: Overall 559 patients with the mean age of 27.2±23.65 years and including 343 (61.4%) males and 216 (38.6%) females were enrolled in this study. The average burn TBSA% was 31.38±24.41% (1-100%). Duration of hospital stay ranged from 1 to 67 days (15.11±10.64). With 93 expired patients, the mortality rate was calculated to be 16.6%. The total LA50 was 66.55% (58.4-79.3). Fire was the most common cause of burn injury.Conclusion: Compared to developed countries, in our burn center the LA50 and survival rate of burn patients are lower. This indicates an urgent need for prompt attention in order to improve current policies regarding this public health issue to reduce mortality.