Abstract： Objective To investigate the relationship between transforming growth factor beta-1 (TGF-β1 )gene-509C/T polymorphism and severe chronic periodontitis in Chinese Hans population.Methods TGF-β1-509C/T genotype polymorphism was analyzed in 102 patients with severe chronic periodontitis(periodontitis group) and 102 healthy controls( control group) by polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) method.Results The distributions of TGF-β1-509C/T genotype and allele were significantly different between severe chronic periodontitis group and control group ( P ＜ 0. 05 ). TGF-β1-509CC, CT and TT genotype frequency were 44. 1% ( 45/102 ), 47. 1%(48/102) ,8. 8% ( 9/102 ) in periodontitis group and 29. 4% ( 30/102 ), 51.0% ( 52/102 ), 19. 6%(20/102) in control group, respectively. The relative risk analysis found that C allele carriers had higher risk of suffering from severe chronic periodontitis compared with T allele carriers( OR = 1. 718,95% CI:1. 148 ～ 2. 569 ).Conclusions TGF-β1-509C/T polymorphism is associated with severe chronic periodontitis in Chinese Hans population, and C allele may be an important genetic susceptibility gene for severe chronic periodontitis.