DNA repair capacity(DRC)is correlated with sensi tivity of cancer cells toward platinum-based chemotherapy.We hypothesize that genetic polymorphisms in DNA repair gene XPA(xeroderma pigmentosum group A)and XPG(xeroderma pigmentosum group G)(ERCC5,excision repair cross-complementation group 5),which result in inter-individual differences in DNA repair efficiency,may predict clinical response to platinum agents in advanced non-small cell lung cancer (NSCLC)patients.In this study,we find that the A→G change of XPA A23G polymorphism significantly increased response to platinum-based chemotherapy.Polymorphism in XPG His46His was associated with a decreased treatment response,but was not statistically significant.