Epidemiologic studies suggest that zinc deficiency may be associated with increased risk of cancer. However, few studies have been conducted with zinc supplementation in animals and humans. Most previous intervention studies have used zinc in combination with several other micronutrients, which make them difficult to interpret. Zinc supplementation is associated with decreased oxidative stress and improved immune function, which may be among the possible mechanisms for its cancer preventive activity. Preclinical and clinical studies need to investigate modulation of genetic and epigenetic pathways of carcinogenesis by zinc.