In this study we investigated the effects of antibiotic and intraperitoneal ozone administration on proinflammatory cytokine, antioxidant levels and tissue damage in the treatment of experimentally infectious peritonitis. Thirty-three adult male New Zealand White Rabbits were used. The study consisted of four groups including the non-treatment group (G(1)), antibiotic group (G(2)), ozone group (G(3)) and ozone + antibiotic group (G(4)). Tri-methoprim sulfadimethylprymidine was administered at a dose of 50 mg/kg subcutaneously (s.c.) and amoxicillin sodium at a dose of 15 mg/kg intramuscularly (i.m.). Medical ozone was administered intraperitoneally (i.p.) at a concentration of 30 mu g O-3/ml and dose of 80 ml/kg. Once peritonitis was produced, blood samples were taken from the animals before treatment and at regular intervals following treatment. Blood samples were used for haemo-grams and to measure levels of antioxidant and oxidative enzymes and pro-inflammatory cytokine levels. Tissue samples were examined histopathologically. There was no statistically significant difference between groups with respect to levels of pro-inflammatory cytokines. Antioxidant enzymes were found to be higher in groups G(2) and G(3). The granulocyte and lymphocyte values in group G(3) were determined to increase earlier than in the other groups. The peritonitis scores were similar in G(1) and G(3), which is higher compared to G(2) and G(4) groups. Minimal tissue damage was observed in the group G(2). It was concluded that antibiotic use for preventing peritoneum damage in experimental acute peritonitis was more effective than ozone therapy alone.