Abstract: Objective :To evaluate the effect of the polymorphisms of excision repair cross complementation group 1(ERCC1) and X-ray repair cross complementing 1(XRCC1) on the overall survival of advanced colorectal can-cer patients who received oxaliplatin-based chemotherapy. Methods :DNA was extracted from peripheral ve-nous blood of 99 advanced colorectal cancer patients before chemotherapy.Real-time PCR was used to typethe SNP of ERCC1 and XRCC1.The patients were routinely treated with oxaliplatin-based chemotherapy.The relationship between time to progress (TTP) and genotypes was explored. Results :ERCC1 Asn118Asnhad three allelotypes including C/C,C/T,and T/T,with frequencies of 50.51%,41.41%,and 8.08%,respective-ly.XRCC1 Arg399Gln had three allelotypes including G/G,G/A and A/A,with frequencies of 52.53%,38.38%,and 9.09%,respectively.The mTTP of these 99 patients was 7 months.The mTTP was 10 month for patientswith C/C genotypes of ERCC1 gene and 5 months for patients with C/T and T/T genotypes of ERCC1 gene,with a significant difference ( P <0.01).The mTTP was 10 months for patients with G/G genotypes of XRCC1gene and 5 months for patients with G/A and A/A genotypes of XRCC1 gene,with a significant difference ( P <0.01).These two polymorphisms seemed to have a synergic effect.The mTTP of patients with ERCC1 C/Cand XRCC1 G/G,ERCC1 C/C and XRCC1 G/A+A/A,ERCC1 C/T+T/T and XRCC1 G/G,ERCC1 C/C+T/Tand XRCC1 G/A+A/A was 11 months,6 months,5 months and 5 months,respectively,with a significant differ-ence ( P <0.01). Conclusion :ERCC1 Asn118Asn and XRCC1 Arg399Gln genetic polymorphisms may be asso-ciated with TTP of advanced colorectal cancer patients treated with oxaliplatin as the first-line chemotherapy.