Fournier's gangrene is a necrotizing infection of skin and soft tissue of the perineum. Several sources of contamination have been described: cutaneous, urological or anorectal. Anatomy of the perineum helps in the prediction of the extension of the infection. The bacterial flora (usually mixed aero-anaerobic flora) depends on the source of infection: gram-positive cocci (skin source) combined with gram-negative bacilli and anaerobes (urological or anorectal source). CT scan and echography are useful tools for the diagnosis without delaying surgery. In the diagnostic procedure and the management, proctological examination, retrograde uretrography, bowel and urine derivation should be discussed.