Background. Systemic administration of antibiotics or selective decontamination is frequently used in the prophylaxis and treatment of infections originating from the gastrointestinal flora. In this study, we wanted to compare. the protective effect of enteral administration of lactobacilli to gentamicin against severe intra-abdominal infection. Methods. Male Sprague Dawley rats underwent cecal ligation and puncture (CLP). Rats were pretreated with saline, Lactobacillus R2LC, and gentamicin. Bacterial growth and endotoxin levels in the blood, reticuloendothelial system (RES) function, and intestinal transit were determined up to 24 hours after CLP. Results. CLP-provoked bacteremia was significantly reduced by 48% and 55% in lactobacilli- and gentamicin-treated rats, respectively. Notably, CLP-induced endotoxemia was abolished at 12 hours, and reduced by 47% at 24 hours, in rats pretreated with lactobacilli., Gentamicin reduced endotoxin levels provoked by CLP by 86% at 12 hours, but had no effect at 24 hours. Lactobacilli had no effect on the clearance of Escherichia coli (E coli) from the blood, whereas intestinal transit was increased in lactobacilli-treated animals, suggesting that the beneficial effect of Lactobacillus R2LC is not related to an increase of phagocytic capacity but may rather be partly attributable to an enhanced intestinal motility. Conclusion. Enteral administration of Lactobacillus R2LC attenuates bacteremia and endotoxemia associated with intra-abdominal infection in rats.