Genome-wide association studies (GWAS) have emerged as a new approach for investigating the genetic basis of complex diseases. In oncology, genome-wide studies of nearly all common malignancies have been performed and more than 100 genetic variants associated with increased risks have been identified. GWAS approaches are powerful research tools that are revealing novel pathways important in carcinogenesis and promise to further enhance our understanding of the basis of inherited cancer susceptibility. However, "personal genomic tests" based on cancer GWAS results that are currently being offered by for-profit commercial companies for cancer risk prediction have unproven clinical utility and may risk false conveyance of reassurance or alarm.