Abstract: Objective To investigate the relationship between DNA repair rate（DRR）of peripheral blood lymphocytes（PBLCs）and the efficacy of platinumbased chemotherapy for patients with advanced gastric cancer. Methods The DRRs of PBLC in 47 patients with advanced gastric cancer and 20 controls without cancer were detected by single cell gel electrophoresis（SCGE）. All the patients received platinum-based chemotherapy and the efficacy was evaluated. The DRRs before platinum exposure and after exposure followed by renovation were analyzed between both groups. The relationship between DRRs of patients with advanced gastric cancer and clinicopathological characteristics or efficacy of platinumbased chemotherapy were investigated. Results SCGE test showed that DRRs of advanced gastric cancer patients by tail length（Z=4.662，P=0.000）and tail moment（Z=3.827，P=0.000） were significantly lower than those of control group. The DRRs were not related to age，gender，ECOG score，histological differentiation and alcohol habits. Fortythree of 47 patients were considered evaluable for efficacy. There were CR in 1 case，PR in 12 cases，SD in 13 cases and PD in 17 cases with the disease control rate of 60.5％. A relatively negative correlation was observed between DRR by tail length and the clinical efficacy （r=-0.327，P=0.032）, while no correlation was observed between tail moment and efficacy(r=0.143, P=0.361). Conclusion Compared with non-cancer populations，patients with gastric cancer have lower DNA repair capacity. The DRR in PBLCs can predict the short-term efficacy of patients with gastric cancer treated with platinumbased chemotherapy.