Background:  Fournier’s disease is a potentially fatal, acute, gangrenous infection of the scrotum, penis or perineum associated with a synergistic bacterial infection of the subcutaneous fat and superficial fascia. Methods:  The clinical records of 70 patients treated for Fournier’s gangrene were evaluated retrospectively to determine prognostic indices and to stress Fournier’s Severity Index (FSI), influencing outcome. Results:  The mortality rate in this study was 22.8%. Length of the hospitalization time and FSI were detected as effective factors on mortality of Fournier’s gangrene (P < 0.05) by Binary Logistic Regression analysis and the area under the receiver operating characteristic curve of these variables was also found to be significant (P < 0.001). The average FSI was determined as 4.66 ± 2.31 in survivors and 11.56 ± 2.68 in non‐survivors and 5.11 ± 2.83 in patients with primary genito‐urinary infection but 7.56 ± 4.35 in primary anorectal infection. The FSI was also found predictive of hospitalization time and number of debridements among survivors. Conclusion:  Fournier’s Severity Index is a simplified way of comparing patients with this disease and may also have some significance in predicting outcome. The FSI is a more significant and predictive tool that should be popularized to predict the prognosis in Fournier’s gangrene.