Autoimmune diseases of the thyroid gland (ADTG) which include, Graves' disease, Hashimoto thyroiditis, primary hypothyroidism with atrophic thyroiditis, postpartum thyroiditis and 'silent' thyroiditis, are characterized by the presence of serum thyroid autoantibodies (TAB). Thyroid autoantibodies are not rare even in the general population of all ages, and their presence in women is 5 times more than in men. The aim of our study was to define the prevalence of thyroid autoantibodies in patients on chronic treatment by amiodarone (AMD), an antiarrhythmic drug rich in iodine, with a potential cytotoxic effect. We have used a section study during a period of two years. Ninety six consecutive patients under AMD treatment were studied, 55 men and 41 women (mean age 62.2 years, range 26-82 years) who referred to us to study their thyroid function. Our results showed that antithyroid antibodies in patients under AMD treatment, with or without thyroid dysfunction, were in similar concentrations as in the general population. A statistically significant greater frequency of increased thyroid peroxidase antibodies (TPOAb) was present in female patients under AMD treatment. When AMD treatment lasted longer than 24 months, the TPOAb were statically higher as compared to those patients under AMD treatment for less than 24 months.