The current therapies used to treat sepsis are ineffective and sepsis-related mortality is high. Therefore, it is important to find new treatment options that reduce mortality from that disease. In the present study, the effects of probiotic pretreatment in septic rats were studied on morality, hematological parameters, oxidative stress, antioxidant capacity and inflammation. After preparation of rats and administration of probiotic VSL # 3, cecal ligation and puncture (CLP) surgery was used to induce sepsis. Then, the animals were divided into four groups: sham, sham + VSL # 3, septic and septic + VSL # 3. Sepsis-related mortality, hematological parameters, and biochemical factors were assessed. Also, the expression of inflammatory cytokines IL-6, TNF-α and IL-10 and NF-κB protein expression were studied using enzyme-linked immunosorbent assay (ELISA). Then, the NF-κB gene and protein expression in intestinal tissue was studied by RT-PCR and western blot techniques, respectively. Daily pretreatment with VSL # 3 in septic rats resulted in a 20% reduction in mortality over 10 days and a significant modulation in hematological parameters. Evaluation of oxidant and antioxidant indices showed a decrease in oxidative stress and an increase in antioxidant capacity in septic rats receiving VSL # 3. Also, decreased expressions of inflammatory cytokines IL-6, TNF-α, IL-10 and NF-κB protein were observed in septic rats receiving VSL # 3. In general, it can be concluded that the administration of probiotic VSL # 3, which resulted in the improved survival of septic rats and better antioxidant and anti-inflammatory conditions, can be considered as a new adjutant therapeutic approach in the treatment of sepsis.