Abstract: Certain types of cancers are attributed to the damaging effects on free radicals or reactive oxygen species (ROS) produced as a by product during the normal oxidative metabolism. It is a commonly held belief that the long-term regular supplement of antioxidants in appropriate quantities helps to minimize the harmful effects of ROS. This article provides a consolidated review on the existence, mechanism of action at molecular level, and effectiveness of antioxidants in cancer prevention. The studies reviewed here indicated that there is a growing evidence which suggested a preventive role played by antioxidants against fatal diseases such as cancer and cardiovascular disease.