Abstract: Objective:Gastric cancer is one of the most common malignant tumors. Chemotherapy is an important part of gastric cancer treatment, especially for advanced gastric cancer patients. Gene polymorphism can affect the metabolism, transportation, and target of medicine, resulting in individual differences. To find a biological marker to identify the patients who can get benefits from the treatment has become a big challenge. The aim of this study was to investigate the correlation between genetic polymorphisms of the X-ray repair cross-complementing group 1 (XRCC1) genes and the clinical outcome of advanced gastric cancer patients treated with DDP-based chemotherapy.Methods:A total of 59patients pathologically diagnosed with advanced gastric cancer were collected. DNAs of peripheral blood leukocytes of these patients were obtained before chemotherapy and were analyzed for XRCC 1399 genotypes by PCR-LDR method. Then all of the patients were treated with chemotherapy of DOCETAXEL combined with 5-FU and DDP. The relationship between the gene polymorphism XRCC 1399 and therapeutic effect was investigated. Results: The frequencies of XRCC1399 genotype were analyzed. A/A was 27.12% , G/A was30.51% , and G/G was 42.37% . The total response rate to chemotherapy was 30.51%. Four patients had complete response,14had partial response, 19had stable disease and 22 had progressive disease. However, the response rate in patients with A/A genotype (68.75%) was significantly higher than that in patients with G/A genotype ( 22.23%) and those with G/G genotype (12.0%), with a significant difference (P<0.01).No significant difference was found in response rate between patients with G/A genotype and patients with G/G genotype (P>0.05). Conclusion:XRCC 1399 polymorphism can predict the therapeutic effect of DDP-based chemotherapy on advanced gastric carcinoma. Patients with XRCC1399A/A genotype are more sensitive to DDP-based chemotherapy than those with other two genotypes.