To evaluate the relationship between alcohol drinking, XRCC1 codon 194 and 399 polymorphisms and risk of colorectal cancer, we conducted a case-control study with 315 colorectal cancer cases (105 colon, 210 rectal) and 439 population-based controls in Jiangsu Province of China. The XRCC1 codon 194 and 399 genotypes were identified using polymerase chain reaction and restrictrion fragment length polymorphism methods (PCR-RFLP). A structured questionnaire was used to elicit detailed information. Odds ratios (ORs) were estimated with an unconditional logistic model. In this study no significant differences were observed among the studied groups with regard to the genotype distribution of the XRCC1 codons 194 and 399 and the risk of colorectal cancer did not appear to be significantly influenced by genotype alone, whereas alcohol consumption showed a positive association (P for trend <0.01). When combined effects of XRCC1 polymorphisms and alcohol consumption were analyzed, we found that the 194Trp or 399Gln alleles further increased the colorectal cancer risk due to high alcohol intake. These findings support the conclusion that colorectal cancer susceptibility may be altered by gene-environment interactions.