Prostate cancer is the second most incident cancer among male population worldwide. Radiation therapy by itself or along with surgery and chemotherapy are the main treatments for prostate cancer however prostate cancer cells are only modestly responsive or even unresponsive to the cytotoxic effects of radiotherapy. Recently some in vitro and in vivo studies showed radiosensitizing and radioprotective effects for curcumin. No clinical trial has been done in this area and it is not yet known whether radiation therapy is more effective with or without curcumin supplements in treating patients with prostate cancer.