Sorghum bicolor L. Moench(Sorghum, Su-Su) is a major cereal food crop used in many parts of the world. It is used as a human food resource and folk medicines in Asia and Africa. The stem of sorghum has been used as a digestive aid and an anti-diarrheal agent. Sorghum hybrids contain high levels of diverse phenolic compounds that may provide health benefits. High levels of polyflavanols, anthocyanins, phenolic acids, and other antioxidant compounds have been reported in sorghums, which have also been shown to possess various biological activities such as anti-mutagenic, anti-carcinogenic, and HMG-CoA reductase inhibitory activities. In an in vitro experiment, we examined mice splenocyte proliferation and production of three types of cytokine($IL-1{eta},;IL-6,;TNF-{alpha}$) by peritoneal macrophages cultured with ethanol and water extracts of Sorghum bicolor L. Moench. A single cell suspension of splenocytes was prepared and the cell proliferation of the splenocytes was examined by MTT assay. The splenocyte proliferation was increased when water extracts of Sorghum bicolor L. Moench were used as supplements in all concentrations investigated. The production of cytokine($IL-1{eta},;IL-6,;TNF-{alpha}$) by activated peritoneal macrophage was detected by ELISA using the cytokine kit. $IL-1{eta},;IL-6,;and;TNF-{alpha}$ production by activated macrophages were increased by supplementation with Sorghum bicolor L. Moench water extracts. This study suggests that supplementation of with Sorghum bicolor L. Moench water extracts may enhance immune function by regulating the splenocyte proliferation and enhancing the cytokine production by activated macrophages in vitro.