Anti-thyroid autoantibodies have been described in anti-hepatitis C virus (HCV)-positive patients. It has been suggested that the anti-GOR response is closely related to HCV infection and may reflect an HCV-associated autoimmune phenomenon. This study was designed to evaluate the humoral anti-GOR response in anti-HCV-positive patients with anti-thyroid autoantibodies (group 1, 22 patients) and to compare it with the response in anti-HCV-positive patients without anti-thyroid autoantibodies (group 2, 44 patients) and in anti-HCV-negative patients with autoimmune thyroiditis (group 3, 28 patients). The prevalences of anti-GOR in groups 1, 2, and 3 were, respectively, 72.7, 61.3, and 3.5%. Anti-GOR levels were higher in group 1 than in group 2 or group 3 (P = 0.0001). Moreover, comparison of the Anti-GOR levels of groups 1 and 2 also revealed a statistically significant difference (P = 0.008). Detection of more elevated anti-GOR levels in group 1 patients suggests that anti-thyroid autoantibodies in anti-HCV-positive patients may be related to HCV.