ABSTRACT Objective To evaluate risk factors for mortality in patients with Fournier's gangrene (FG), with emphasis in the Simplified Fournier Gangrene Severe Index Score (SFGSI). Materials and Methods This was a cross-sectional study that was carried out from January 2010 to December 2014, with 124 patients treated for FG in a General Hospital. Several clinical and laboratory variables, including SFGSI, were evaluated and correlated with mortality through univariate analysis and logistic regression. Results Of the 124 patients, 99 were men (79.8%), the mean age was 50.8±19.5 years and the main comorbidity was diabetes mellitus (51.6%). The mortality rate was 25.8%. Variables that presented independent correlation with mortality were the extension of the lesion to the abdomen (OR=4.0, CI=1.10-14.68, p=0.03), hematocrit (OR=0.81, CI=0.73-0.90, p<0.0001), potassium (OR=2.41, CI=1.13-5.10, p=0.02) and creatinine (OR=2.15, CI= 1.04-4.41, p=0.03). When hematocrit, potassium and creatinine were tested together, as part of the SFGSI, a >2 result was the largest of the independent predictors of mortality (OR=50.2; CI=13.18-191.47; p<0.0001). Conclusion The SFGSI >2 presented a higher correlation with mortality than any variable tested alone. It seems to be a promising alternative to evaluate predictors of mortality in Fournier's gangrene. The main advantage is easy applicability because it contains only three parameters and can be used immediately after patient's admission.