Recent advances in genomic and postgenomic research revealed that genetic variations of drug metabolism enzymes (DMEs) genes influence each individuals specific responses toward the exposure of drugs,pollutants,and precarcinogens.Colorectal cancer (CRC) is an important cause of death from cancer in the developed countries.Comparison of CRC rates in different countries revealed marked regional differences again implicating the combined influence of genetic and local environmental factors such as carcinogen exposure and diet.The influence of specificdietary and lifestyle habits on the development of CRC as well as the interaction of these factors with genetic predispositions has been proposed to be critical for CRC.In a case control study including more than 250 of sporadic CRC patients and health controls of the Chinese population,we mapped the single nucleotide polymorphisms (SNPs) for several candidate genes involved in Phase I and Phase Ⅱ xenobiotic metabolism.