Abstract: Objective To explore the interaction of polymorphisms of ameloblastin(AMBN) gene and environmental factors in endemic fluorosis.Methods A case-control study was carried out and Duping township of Wushan county and Xinglong township of Fengjie county in Chongqing municipality were chosen as fluoride areas.The observation subjects were divided into a case group(121) and a control group(121 in the endemic areas).Polymerase chain-reaction restriction fragment length polymorphism(PCR-RFLP) was used to determine the polymorphisms of AMBN.Interaction indexes(γ)were calculated to determine the type of gene-environmental interation.Conditioned logistic regression analysis was adopted in data analysis with SPSS.Results Urinary fluoride of ≥0.95 mg/L was interacted with the genotypes(538_540delGGA)-/- of exon 7(odds ratioOR=5.600, y=1.543)and genotype(986C>T)CT of exon 13(OR=4.375, y=1.296) in AMBN in the incidence of endemic fluorosis.Conclusion Genotypes of 538-540 delGGA-/- and(986C>T)CT in AMBN may interact with urinary fluoride(≥0.95 mg/L)in the incidence of coal-burning fluorosis.