Epidemiological evidence on the relationship between IL1A and/or IL1B polymorphisms and periodontal disease is inconsistent. We investigated associations between three IL1 single-nucleotide polymorphisms (SNPs) in genes encoding interleukin (IL) -1α (rs1800587) and IL-1β (rs1143634 and rs16944) and the risk of periodontal disease among young Japanese women. A case-control study was performed with a total of 1150 women, including 131 subjects who had at least one tooth with a probing pocket depth of 4 mm or deeper and 1019 periodontally healthy controls. Compared with a reference group of women with the GG genotype of SNP rs16944, those with the GA genotype had a significantly reduced risk of periodontal disease, while there was no significant relationship between the AA genotype and periodontal disease. No evident relationships were observed between SNP rs1800587 or rs1143634 and periodontal disease. Our study did not reveal any evidence of interaction between the IL1 polymorphisms and smoking. The results of this study showed that the heterozygous variant genotype of the IL1 rs16944 was significantly associated with a reduced risk of periodontal disease in young Japanese women. Smoking did not significantly modify the gene-disease associations under study.