Colonic resection and anastomosis is one of the most common operations in gastrointestinal surgery, both in children and adults. Although these are safe operations, an anastomosis leakage is a frequent problem (1, 2). Age, condition of the patient, colonic flora, inflammation and surgical techniques are the most important factors affecting the outcome of these procedures (3, 4). The presence of peritonitis is a defining factor of anastomosis integrity.The cecal ligation and puncture (CLP) model was first defined by Hubbard et al. (5) in 1978 to induce peritonitis. Several studies suggest that in the presence of peritonitis, wound healing worsens and anastomotic leakage increases. To avoid these unwanted effects of peritonitis on wound healing and to increase anastomosis security, various methods and local or systemic agents are being investigated.Ozone is a three-oxygen molecule (O 3 ). Ozone therapy (OT) is systematically effective when pathological inflammatory and immunologic processes are activated. Among these conditions are wound healing, macular degeneration related to aging, and conditions that are ischemic or infectious.During OT, the gaseous mixture of oxygen and ozone exerts biological actions that may increase certain enzymes and cytokines. Ozone provides its protective effects via autacoids, cytokines, and growth factors. Recurrent OT corrects the disBackground: Ozone is a three-oxygen molecule (O3). Ozone therapy (OT) is systematically effective when pathological inflammatory and immunologic processes are activated. Among of these conditions are wound healing, macular degeneration related to aging, and conditions that are ischemic or infectious. Aims: The aim of this study was to determine the effects of OT on wound healing of intestinal anastomosis in the presence of peritonitis in a rat model. Study Design: Animal experimentation. Methods: A total of 40 Wistar albino rats were randomized into four groups (n=10) including: sham (S), peritonitis (P), ozone 0 (O0), and ozone 24 (O24). In group S, only cecal dissection was carried out. The S group had only a cecal dissection and intestinal anastomosis performed, but no peritonitis. In all other groups, cecal ligation and puncture (CLP) followed the cecal dissection to induce bacterial peritonitis. 24 h after puncture, a cecal resection and ileocolic anastomosis were performed. In group P, 24 h after CLP, a cecal resection and ileocolic anastomosis were performed and no ozone was administered. In group O0, immediately after the anastomosis, and in group O24, starting 24 hours after the anastomosis, an intraperitoneal 1 mg/ kg/day ozone administration was applied for seven days. On the seventh day the animals were sacrificed, the anastomotic bursting pressures (BP) and the hydroxyproline values of the anastomotic tissues were measured, and histopathologic examination of the anastomotic segment was carried out. Results: The highest BP was in group S, with 211±23.13 mmHg. The mean BP of group P was 141±56.25 mmHg, which was significantly lower than in t...