Objective To explore the associations between polymorphisms in CYP24A1 gene and the risk and prognosis of colorectal cancer ( CRC) .Methods A case-control study consisting of 528 CRC patients and 605 cancer free controls and a follow up study with 317 cases were conducted to explore the associations be-tween two polymorphisms in CYP24A1 and the risk and prognosis of CRC,as well as the combinations and inter-actions of polymorphisms with dietary factors on CRC risk.Results Although there was no association between polymorphisms in CYP24A1 and the risk of CRC,significant combinative effects between polymorphisms and diet-ary factors on CRC risk were observed.For Rs4809957 polymorphism,the prognosis of AA genotype carriers was worse than GG/GA carriers in CRC,colon cancer and rectal cancer(Log-rank test P=0.01,P=0.01,P=0.02,respectively).Compared with GG genotype,AA genotype carriers of Rs4809957 polymorphism had worse prognosis in CRC(HR =2.35,95%CI =1.28~4.30),colon caner(HR =2.37,95% CI =1.09~5.14) and rectal cancer(HR =2.11,95% CI =1.11~4.01).Conclusion The combinations of the polymorphisms in CYP24A1 gene with dietary factors are associated with the susceptibility of CRC,and Rs4809957 polymorphism may lead to a worse prognosis of CRC.