Carcinogenesis is a multistage process derived from a combination of multiple heritable and environmental factors. It has been reported that populations consuming high levels of soybean products have both lower cancer incidence and mortality rates in the western countries. Lunasin is a novel and promising peptide initially discovered in soy and now found in wheat, barley and other seeds. Its cancer-preventive efficacy has been shown in mammalian cells which were induced by chemical carcinogens and viral oncogenes. Moreover, this peptide has been found to prevent skin cancer in a mouse cancer model induced by chemical carcinogens. Its bioavailability after oral administration makes it a perfect candidate as a chemopreventive agent. The purpose of this article is to review the discovery of this seed peptide and the most recent evidence on its possible benefits as an anticancer agent.