This study was performed to investigate the in vitro effect of a corn water extract on immune function. Splenocyte proliferation was determined by the MTT(3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl terazolium bromide) assay after preparing asingle cell suspension. Production of macrophage-secreted interleukin(IL)-$1{eta}$, IL-6, and interferon(IFN)-${gamma}$, was detected by ELISA using a cytokine assay kit. After a 48-hr incubation with mitogens(ConA or lipopolysaccharide), mice splenocyte proliferation increased with the addition of a corn water extract supplement at 10, 50, 100, 250, 500, or $1,000;{mu}g/mell$. Production of IL-$1{eta}$, IL-6, and IFN-${gamma}$ increased in treatments supplemented with the corn water extract. In an in vitro study, splenocyte proliferation increased when $50sim1,000;{mu}ell/mell$ corn water extract was added. In an ex vivo experiment, the highest production of cytokines by activated peritoneal macrophages was observed in mice orally administered 500 mg/kg body weight/day.