The lethal toxin of Bacillus anthracis, which is composed of two separate proteinaceous exotoxins, namely protective antigen and lethal factor, is central to the pathogenesis of anthrax. Low levels of this toxin are known to induce release of cytokines such as tumor necrosis factor alpha (TNF-alpha). In the present study we investigated the effect of dehydroepiandrosterone (DHEA), melatonin (MLT), or DHEA + MLT on production of lethal toxin-induced TNF-alpha in mouse peritoneal macrophages. We found that treatment with DHEA significantly inhibited the TNF-alpha production caused by anthrax lethal toxin. Exposure of MLT to anthrax lethal toxin-treated macrophages also decreased the release of TNF-alpha to the extracellular medium as compared to the control. However, combined use of DHEA and MLT also inhibited TNF-alpha release, but not more than single therapies. These results suggest that DHEA and MLT may have a therapeutic role in reducing the increased cytokine production induced by anthrax lethal toxin.