This review summarizes current knowledge on the anticarcinogenic properties of garlic. Collectively epidemiologic studies – mostly casecontrol studies – provide strong evidence that garlic consumption reduces the risk of cancer especially, the risk of gastric and colon cancer. Furthermore many experimental studies demonstrate that organosulfur compounds (OSCs) and garlic extracts can prevent or slow down the carcinogenic process induced by a variety of chemical carcinogens in animals. Garlic and OSCs have been shown to be active during all the stages of carcinogenesis. Several mechanisms have been proposed to explain the cancer-preventive effects of garlic and related OSCs. These include inhibition of the carcinogen formation, antioxidant action, inhibition of genotoxicity and/or mutagenicity of carcinogenic agents, modulation of the carcinogen metabolizing enzymes, effect on cell proliferation and apoptosis, and inhibition of angiogenesis. While research on garlic is promising, the outcome can not be directly translated in specific recommendations for garlic consumption. However this outcome must sustain the general recommendation of consuming daily a variety of vegetables and fruits.