In this study, we investigated the association between genetic polymorphisms of XRCC1 Arg399Gln (G→A) and response to oxaliplatin-based chemotherapy in advanced colorectal cancer. XRCC1 genotypes of totally 99 patients (37 stage III and 62 stage IV) with advanced colorectal cancer treated with oxaliplatin-based chemotherapy were detected by the TaqMan-MGB probe allelic discrimination method, and clinical response of 62 patients in stage IV after 2 to 3 cycles of chemotherapy were evaluated. Also, time to progression (TTP) of all patients was evaluated. The results showed that of the genotype frequencies in all patients, up to 52.53% were G/G genotype, 9.09% were A/A genotype, and 38.38% were G/A genotype. The response rate (CR + PR) of 62 patients in stage IV was 61.29% (19/31). Patients with G/G genotype showed enhanced response to chemotherapy compared with those with G/A + A/A (x(2) = 5.6, p = .029; Odds Ratio (OR) = 3.845, 95% Confidence Interval (CI) = 1.231 ∼ 12.01, p = .018). Individuals with the G/G genotype had a TTP of 10.0 (8.88-11.12) months, and those with the G/A + A/A genotype had a TTP of 5.0 (4.26-5.74) months. The Log-Rank test was marginally significant (x(2) = 29.20, p < .01). The Cox proportional hazards model, adjusted for stage, performance status, and chemotherapy regimen showed that only XRCC1 G/G genotype increases the OR significantly (OR = 3.555; 95% CI, 2.119 ∼ 5.963; p < .01). These results indicate that XRCC1 Arg399Gln polymorphism is associated with response to oxaliplantin-based chemotherapy and TTP in advanced colorectal cancer in Chinese population. It is proposed that the XRCC1 Arg399Gln polymorphism should be routinely detected to screen patients who are more likely to benefit from oxaliplantin-based treatment.