Hashimoto's disease is a polygenic disorder with complex etiopathogenesis. The imbalance between pro- and anti-inflammatory cytokines may play a role in the etiology. We aimed to evaluate the relation between 174 promoter region of the interleukin 6 rs1800795 gene polymorphism in patients with Hashimoto's thyroiditis (HT). We studied 110 HT patients and 110 healthy controls. The evaluation of genotype for interleukin 6 rs1800795 gene polymorphism were performed by using PCR-RFLP method. The genotype of IL6 distribution did differ between the control group (CC 17.3%, GC 78.2%, GG 4.5%) and the HT patients (CC 29.1%, GC 46.4%, GG 24.5%) (p < 0.001). The frequency of the polymorphic G allele was similar for the group with HT patients as the control group with 47.7% and 43.6%, respectively (p > 0.05). Our results indicate that interleukin 6 rs1800795 polymorphism may be associated with susceptibility to HT in Turkish Patients. It is necessary to confirm the results and determine the underlying pathogenic mechanisms in further studies. (C) 2016 Elsevier B.V. All rights reserved.