PURPOSE: Janus kinase 2 (JAK2) and signal transducer and activator of transcription 3 (STAT3) polymorphisms have been demonstrated as a common risk factor for a number of autoimmune diseases. The aim of this study was to investigate the association of JAK2 and STAT3 polymorphisms with Behcet's disease (BD) in a Han Chinese population. METHODS: A case-control study was performed in 503 Chinese patients with BD and 615 healthy controls. The genotypes of three single-nucleotide polymorphisms (SNPs) (rs10758669, rs7857730, rs10119004) in the JAK2 and four SNPs (rs6503695, rs744166, rs2293152, and rs12948909) in the STAT3 gene were analyzed using polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP). In all, 10% of the samples were sequenced to validate the result of PCR-RFLP. The chi(2) test was performed to compare allele and genotype distributions and Bonferroni correction was applied for multiple comparisons. RESULTS: A deviation from the Hardy-Weinberg equilibrium was not found in all controls tested. A significantly increased frequency of the GG genotype of the STAT3 rs2293152 was observed in patients with BD (Bonferroni-corrected P value = 0.021). None of the tested SNPs of JAK2 was associated with BD. Stratification analysis according to oral ulceration, genital ulceration, skin lesions, and arthritis for BD did not reveal an association. CONCLUSIONS: These results suggest that a STAT3 genetic polymorphism is associated with the susceptibility to BD.