A 68-year-old male diagnosed as carcinoma of the sigmoid colon developed shock and cardiac arrest just 8 hours after the onset of ielus. After resuscitation, exploratory laparotomy was carried out and it revealed gangrene spreading from the sigmoid colon over the distal 150cm of the terminal ileum, separated from the carcinoma by a normal segment of the colon 13cm in length. All the mesenteric vessels were pulsating normally. The whole necrotic lesion including the carcinoma was resected and an ileostomy was constructed. This is a noteworthy report of severe obstructive necrotizing enterocolitis with critical condition and wide involvement of the colon and intestine associated with carcinoma of the sigmoid colon.