Fournier's gangrene is a bacterial and rapidly progressive necrotizing fasciitis of the perianal and perineal region. It still has high morbidity and mortality. We aimed to present Fournier's gangrene, which developed in a 49-year-old male patient with substance abuse. The patient was brought to the emergency department with complaints of abdominal pain and pain in the perineum and perianal region on the 3rd day after foreign body trauma to the perianal region. Crepitation was detected under the skin in the suprapubic region of the patient. Acute abdomen was present in the abdominal examination. In the abdominal tomography, minimal fluid was detected between the bowel loops in the pelvis. Diffuse edema, heterogeneity and emphysematous changes were observed in the skin and subcutaneous tissues in the perineum, and in the rectus muscle of the anterior abdominal wall. The patient underwent an emergency laparotomy. Abscess material extending from the back of the rectus muscle to the pelvis was seen in the abdomen. Abscess and necrotic areas in the abdomen and perineum were cleaned. A protective Hartman end colostomy was opened to the patient. In the postoperative period, VAC was applied to the perianal region for 3 sessions with 72 hour intervals. Then, the wound in the perineum was closed primarily. After 3 months, his colostomy was taken into the abdomen. Early and aggressive surgical debridement, broad-spectrum antibiotics, and fluid resuscitation are critical in Fournier's gangrene. Because of this patient's late admission to the hospital and his long-term immunosuppression associated with substance abuse, his clinical condition deteriorated rapidly. It should be kept in mind that skin infections in the perianal region may progress to Fournier's gangrene in patients with conditions that may cause immunosuppression, such as substance abuse.