Background: Numerous studies have demonstrated that nasopharyngeal carcinoma (NPC) has a complex etiology involving multiple genes,environmental factors as well as their interplays.DNA repair system takes an important role in modulating DNA repair capacity and stabilizing individual inheritance.Methods: To identify whether DNA repair genes and some nongenetic factors that increase the susceptibility to NPC development,a case-control study was conducted to evaluate the interaction between the selected DNA repair genes and environmental factors among the living habits of Cantonese population in Guangdong Province,China.622 SNPs covering 88 DNA repair genes were genotyped and 3 environmental factors were collected in a case-control study (cases/control=755/755).The interactions were estimated by an ensemble decision forest method.