Sorghum bicolor L. is one of the important minor cereals in Asia, Africa, and the central United States, and it is considered a rich source of polyphenols, flavonoids, and dietary fiber. However, there is a lack of data on the anti-cancer activity of Sorghum in prostate cancer cells and immune activity in macrophages. This study aims to investigate the potential effects of an ethanol extract of S. bicolor L. (SE) on inducing apoptosis in RC-58T/h/SA#4 cells and immunomodulatory activity in RAW 264.7 cells. SE significantly inhibited the viability of RC-58T/h/SA#4 primary prostate cancer cells in a dose-dependent manner. The morphology of RC-58T/h/SA#4 cells treated with SE was shrunken and involved the formation of an apoptotic body and nuclear condensation. In addition, SE markedly activated caspase-8, -9, and -3; increased the protein levels of Bax, p53, cleaved PARP, and cytosolic cytochrome c; and decreased Bcl-2 protein expression. Furthermore, the inhibition of caspases in RC-58T/ h/SA#4 cells with z-VAD-fmk attenuated SE-induced cell growth inhibition. The production of nitric oxide (NO) was also elevated by SE treatment, as revealed by immune response parameters. These results suggest that SE inhibits growth and induces apoptosis in primary human prostate cancer cells in a caspase-dependent manner, and it modulates the immune functions in macrophages. Therefore, Sorghum bicolor L. may be used as a functional food to prevent prostate cancer and enhance immune activity.Key words : Apoptosis, immune activity, RC-58T/h/SA#4, Sorghum ethanol extract