Objective:To investigate the protective role of Ocimum sanctum (O. sanctum) leaves against Salmonella typhimurium(S. typhimurium) infection in rats by inducing TNF-α, IFN-γ& IL-2 cytokines.Methods:Wistar albino rats were fed with aqueous extract ofO. sanctum leaves using 250 mg/kg body weight dose once a day for20 consecutive days. Control rats were fed with placebo. Rats were infected withLD50 dose ofS.typhimuriuminfection and monitored for their survival. Bacterial blood burden in both the groups was compared and numbers of activated peritoneal macrophages were counted. Concentration of TNF-α, IFN-γ and IL-2 cytokines in serum during different time intervals was assayed by sandwich ELISA.Results:Rats of control group showed a high mortality rate and had higher bacterial blood burden when compared with O. sanctum extract fed rats. There was a significant increase in the number ofS. typhimurium engulfed peritoneal macrophages in the peritoneal fluid ofO. sanctum fed animals. The protective control against bacterial infection inO. sanctumfed rats was associated with elevated level of TNF-α, IFN-γ and IL-2 cytokines in serum.Conclusions: These findings suggest that orally administeredO. sanctum leaves extract effectively enhanced activation in macrophage and lymphocytes, depicted by the elevated serum concentration of TNF-α, IFN-γ and IL-2 cytokines, leading to induce a protective resistance againstSalmonellatyphimurium infection.