BACKGROUND: In our study, the effects of peritoneal fluid on some Gram-negative and Candida albicans in experimental peritonitis rats were studied. The primary objective of the present study was to understand the effect of peritoneal fluid on microorganismscausing intra-abdominal infections.METHODS: Twenty male Sprague–Dawley rats weighing between 250 and 300 g were used in the study. The rats were randomlydivided into two groups consisting of 10 animals. The operative procedures were performed under sterile conditions. In group I, shamlaparotomy was done. In group II, the distal part of the cecum was ligated, and cecum perforation was performed. Peritoneal fluidsamples at baseline and 2 and 4 h were extracted using a Pasteur pipette during laparotomy under anesthesia.RESULTS: Peritoneal fluid was ineffective on Citrobacter freundii, Proteus mirabilis, and Enterobacter aerogenes. It inhibited thegrowth of Klebsiella pneumoniae for 8 h. However, growth was significantly increased in the passages obtained after 24 h. The growthof C. albicans decreased in the passages that were extracted after 4 and 8 h and increased in the passages obtained after 24 h (p<0.05).It was found that the number of Escherichia coli and Pseudomonas aeruginosa colonies that were grown in 2 h decreased, and nogrowth was detected in the passages obtained after 2 h (p<0.05).CONCLUSION: Proliferating colony counts of E. coli and P. aeruginosa decreased after 2 h, and there was no proliferation in subsequent cultures. Peritoneal fluid exhibits a bactericidal effect under appropriate conditions. It also exhibits peritoneal bactericidalactivity against E. coli, the major pathogen in intra-abdominal infections.