Background: Numerous animal and in vitro studies provided evidence for a relation between garlic intake and cancer risk reduction. Several studies also reported an inverse association in humans. However, no claims have been made about garlic intake and cancer risk reduction with respect to food labeling. Objective: The objective of this study was to evaluate the scientific evidence for garlic intake with respect to the risk of different types of cancer using the US Food and Drug Administration's evidence-based review system for the scientific evaluation of health claims. Design: Literature searches were conducted by using the Medline and EMBASE databases for the period 1955-2007 with search terms Allium sativum, vegetables, diet, and nutrition in combination with cancer, neoplasm, and individual cancers. The search was limited to human studies published in English and Korean. Results: With the use of the US Food and Drug Administration's evidence-based review system for the scientific evaluation of health claims, 19 human studies were identified and reviewed to evaluate the strength of the evidence that supports a relation between garlic intake and reduced risk of different cancers with respect to food labeling. Conclusions: There was no credible evidence to support a relation between garlic intake and a reduced risk of gastric, breast, lung, or endometrial cancer. Very limited evidence supported a relation between garlic consumption and reduced risk of colon, prostate, esophageal, larynx, oral, ovary, or renal cell cancers.