Antiphospholipid syndrome is characterized by arterial or venous thrombosis and the production of antiphospholipid antibodies. Antiphospholipid syndrome may present primarily or secondary to systemic lupus erythematosus. The clinical features include multiple thrombosis, cerebral diseases, abortion in female, thrombocytopenia and so on. The treatment is based on anticoagulants, steroids, immunosuppressive agents and antiplatelet drugs. We report a case of a 29- year-old man who was admitted to Ewha Womans University Mok-dong Hospital with a generalized peritonitis. On emergency exploratory laparotomy, segmental infarction of the terminal ileum and the right colon was revealed and a right colon and ileal resection was performed. During the postoperative period, the patient was finally diagnosed having antiphospholipid syndrome with systemic lupus erythematosus. He also had ischemic heart disease due to coronary artery thrombosis and pulmonary embolism due to deep vein thrombosis of the lower extremities. He eventually expired following a restorative ileocolostomy owing to anastomotic leakage and sepsis.