AG and GG genotypes of 3’UTR CT60 polymorphism of CTLA4 gene when compared with AA genotype between patients and control by chi-square test-2x2 contingency table showed to increase susceptibility to autoimmune hypothyroidism (p = 0.0110 and odds ratio 4.853; p = 0.0005 and odds ratio 7.174 respectively) (Table 1). This evidence concerns the gene CTLA4 and Hashimoto thyroiditis.