Prostate cancer (PC) is the most common non-cutaneous cancer in the United States male population, and the second most common cause of cancer mortality. It has been proposed that dietary differences in Asian and Western men may be partially responsible for the lower incidence of PC among Asian men. The assumption that the Asian diet may be prostate-healthy is based on the fact that it contains many soy products. The purpose of this study was to determine whether there is a relationship between the consumption of a soy-rich diet and PC incidence. Methodology: A systematic review of evidence-based literature was conducted by examining peer-reviewed articles from the following databases: MEDLINE FirstSearch, MEDLINE PubMed, and Cochrane Library. MeSH terms utilized included prostate cancer/carcinoma, soy, soy-rich diet, prostate cancer incidence, and genistein. The findings suggest there are benefits related to the consumption of a soy-rich diet, but none were shown to be conclusively preventative. More in vivo research must be completed before a statistically significant relationship between the consumption of a soy-rich diet and the incidence of PC can be substantiated.