We previously demonstrated that ginsenosides Rg1 and Re enhanced the immune response in C3H/HeB mice but not in C3H/HeJ mice carrying a mutation in the Tlr4 gene. The results of the present study showed that both Rg1 and Re inhibited mRNA expression and production of proinflammatory mediators that included tumor necrosis factor a, interleukin-1β, interleukin-6, cyclooxygenase-2, and inducible nitric oxide synthase from lipopolysaccharide (LPS)-stimulated macrophages. Rg1 was found to be distributed both extracellularly and intracellularly but Re was located only extracellularly to compete with LPS for binding to Toll-like receptor 4. Preinjection of Rg1 and Re into rats suppressed LPS-induced increases in body temperature, white blood cell counts, and levels of serum proinflammatory mediators. Preinjection of Rg1 and Re into mice prevented the LPS-induced decreases in total white blood cell counts and neutrophil counts, inhibited excessive expression of multiple proinflammatory mediators, and successfully rescued 100% of the mice from sepsis-associated death. More significantly, when administered after lethal LPS inoculation, Rg1, but not Re, still showed a potent antisepsis effect and protected 90% of the mice from death. The better protection efficacy of Rg1 could result from its intracellular distribution, suggesting that Rg1 may be an ideal antisepsis agent.