The aim of this study was to estimate thyroid function and the prevalence of thyroid antibodies among HCV seropositive patients. We undertook a screening for thyroid dysfunction, and antithyroperoxidase (ATPO) and antithyroglobulin (ATG) antibodies, in 215 HCV seropositive patients referred for hepatologic consultation, 118 males and 97 females, mean age 44 +/- 14 years, range 16-80 years. No patient was treated with interferon and all were seronegative for HIV. Eighteen patients (8%) had antithyroid antibodies, 12 with ATPO antibodies (5.6%) and 10 with ATG antibodies (4.7%). Four patients had both ATPO and ATG antibodies (1.8%), one case of Graves' disease and 3 cases of autoimmune hypothyroidism found during this study. Five patients (2.3%) had hyperthyroidism, three cases of Graves' disease, one case of iodine load and a case of Grave's disease incidentally diagnosed during medical examination. Eleven patients (5.1%) had hypothyroidism, one case already known and treated without antithyroid antibodies, 4 cases of autoimmune etiology (3 diagnosed in consultation and one already known and compensated hypothyroidism), one case of amiodarone-induced hypothyroidism discovered during this study, 5 cases of hypothyroidism without antibodies (two cases of compensated hypothyroidism with normal TRH stimulating test, two cases with severe liver cirrhosis and one case with chronic hepatitis). Twelve patients had antithyroid antibodies with normal TSH levels. The prevalence of ATPO and ATG antibodies in our study is similar to the prevalence usually observed in general population and does not suggest a pathogenic role of HCV in autoimmune thyroid disorders.