The study included 80 HCV Egyptians patients eligible for treatment with interferon alpha. Thyroid hormones, thyroid autoantibodies (anti TG Ab, anti-peroxidase Ab and anti TSH Ab), thyroid uptake and scan were performed at basal condition and 3 months after treatment. After 3 months of IFN-α administration, 23/80 patients (28.7%) developed thyroid dysfunction. A statistically significant elevation of thyroid autoantibodies was detected in 58%of patients compared to 36% at basal condition. Do novo thyroid autoimmunity was detected in 22.5% of patients.