Abstract: Objective In order to examine the relationship between the popotymorphism of Interleukin-1β(IL^-1B)⁺³⁹⁵³ allele 2 and susceptibility to moderate to severe adult periodontitis (AP).Methods A case-control study was carried out and polymerase chain reaction(PCR)and restriction fragment length polymorphisms(RFLP)technique was used to identify IL^-1B⁺³⁹⁵³ genotype in 124 cases of moderate to severe adult periodontitis (AP)and 172 controls.Results The frequency of IL^-1B⁺³⁹⁵³ allele 2 positive genotype in patients with moderate to severe AP (28.23%)showed a statistically significant increase compared to the control group frequency(13.95%)(χ²=8.32,P=0.0029,OR=2.425,95%CI=1.35～4.34).Conclusion IL^-1B⁺³⁹⁵³ allele 2 positive genotype is relative to susceptibility of moderate to severe adult periodontitis.