Necrotizing fasciitis is a life-threatening soft tissue infection characterized by progressive necrosis of the skin, subcutaneous tissues and fascia. Fournier's gangrene (FG) is a serious and aggressive form of infective necrotizing fasciitis involving perineal region and genitalia: Presently described are 2 pediatric cases of FG with widespread necrosis of surrounding tissue following anorectal surgery, causing severe septic shock. Case I : Six-month-old female patient with anal stenosis and duplication presented at emergency clinic with fever, somnolence, irritability, and feeding difficulty. Physical examination upon admission to Intensive Care Unit (ICU) with septic shock determined she had ecchymosis in anal region. At 12fth hour after admission, lesion had become necrotic and patient was started on broad-spectrum antibiotics after surgical debridement. Cultures were negative and patient had complete recovery 2 months after admission. Case 2: Nine-month-old male patient was admitted to ICU for convulsions and sepsis eight hours after fistulectomy. Scrotal, gluteal, and perianal edema and ecchymosis were observed on physical examination. Perianal debridement and colostomy were performed, and patient was given broad-spectrum antibiotics after basic life support strategies for septic shock. Complete recovery was achieved after hyperbaric oxygen treatment for perianal lesion and patient was discharged from the hospital in third month after admission. After anorectal surgery, every patient should be observed carefully for FG. Early debridement, proper antibiotics, and hyperbaric oxygen treatment can be life-saving.