Recurrent aphthous stomatitis (RAS) is a common oral inflammatory disease with unknown etiology in which the immune system seems to have a role in oral tolerance. Interleukin (IL)-10 is a cytokine synthesis inhibitory factor. Single nucleotide polymorphisms (SNPs) of IL10 gene could alter this cytokine production. The aim of this study was to investigate frequencies of IL10 alleles and genotypes in a group of individuals with RAS. Genomic DNA of 60 Iranian patients with RAS were typed for IL10 gene (C/A -1082, C/T -819, and C/A -592), using PCR-SSP method. Frequency of each allele and genotype was compared to control group. A significantly higher frequencies of the T allele at position -819 (p=0.006) and the A allele at position of -592 (p<0.001) were found in the patients with RAS group, when compared to the controls. IL10 GA genotype at position -1082 (p=0.007), CA genotype at position -592 (p=0.001), and CT genotype at position -819 (p=0.001) were significantly higher in the RAS patients. The results of this study suggest that certain SNPs of IL10 gene have association with predisposition of individuals to RAS. However, further multicenter studies should be conducted to confirm the results of this study.