Abstract: The aim of this study was to investigate the protective activity of the synbiotics Biomin®Imbo and yoghurt against septic peritonitis in rats. Cecal Ligation and Tip Resection (CLTR) model was followed to induce fecal peritonitis. Effects of the synbiotics on survival after CLTR, acute phase proteins, pathological lesions, the Total and Differential Leukocytic Count (TLC and DLC) of the peritoneal fluid, the TLC and DLC of the peripheral blood and mean bacterial growth in the peritoneal cavity were studied. It was found that neither Biomin®Imbo nor yoghurt in the dose schedule used in this study prevented lethality at the end of the first and third day post induction (p.i.) of CLTR. No significant change was found in the values of the serum c-reactive protein in the various groups. Fibrinogen was elevated significantly in the groups in which septic peritonitis was induced. Gross and microscopic lesions that were observed in groups subjected to CLTR were comparable with those of bacteremia. There were generalized sepsis and fibrinous adhesions that were converted to fibrous adhesions after the 7th p.i. day. No significant change was noted in the cytologyof the peritoneal fluid in the various groups at the end of the first p.i. day. However, the TLC of the peripheral blood was significantly higher in rats of the experimental groups (with septic peritonitis) than in the control group. Yoghurt and to alesser extent Biomin®Imbo were found to lower insignificantly the bacterial growth in the peritoneal cavity at the end of the first p.i. day.