The clinical implications of increased cytokine levels after major surgery remain unclear. This prospective study was designed to determine the peritoneal cytokine response to elective colorectal surgery during the postoperative period to evaluate its role as an indicator of anastomotic leakage. The study comprised 40 patients; 28 (70.0%) males and 12 (30.0%) females, with mean age 49.7±12.6. All patients assigned to elective colonic or colorectal resection according to indicated operative procedure. Intraperitoneal fluid cytokines TNF-alpha, IL-6, IL-10 and IL-1beta levels obtained from abdominal drains were measured for five days. Four patients developed anastomotic leakage and underwent relaparotomoy. A significant increase was observed between peritoneal TNF-alpha, IL-6, IL-10 and IL-1beta levels and postoperative days (P