The thyroid gland has a key role in maintaining the body's homeostasis. Thyroxine (T4) is the main hormone secreted from the thyroid gland, its effect being predominantly achieved after the intracellular conversion of thyroxine to triiodothyronine (T3), which exhibits a higher affinity for the receptor complex, thus modifying gene expression of the target cells. Amiodarone is one of the most commonly used antiarrhythmics and is used in the treatment of a broad spectrum of arrhythmias, usually tachyarrhythmias. Amiodarone contains a large proportion of iodine, which is, in addition to the intrinsic effect of the medication, the basis of the impact on thyroid function. It is believed that 15-20% of patients treated with amiodarone develop some form of thyroid dysfunction. Amiodarone may cause amiodarone-induced hypothyroidism (AIH) or thyrotoxicosis – AIT (amiodarone induced thyrotoxicosis). AIT is usually developed in the areas with too low uptake of iodine, while AIH is developed in the areas where there is a sufficient iodine uptake. Type 1 AIT is more common among the patients with an underlying thyroid pathology, such as nodular goiter or Graves (Basedow) disease, while Type 2 mostly develops in a previously healthy thyroid. AIH is more common in patients with the from before diagnosed Hashimoto's thyroiditis. Combined types of diseases have also been described. Patients treated with amiodarone should be monitored regularly, including laboratory testing and clinical examinations, to early detect any deviations in the functioning of a thyroid gland. Supplementary levothyroxine therapy is the basis for the AIH treatment. Often, in such cases it is not necessary to cease the amiodarone therapy. Type 1 AIT is treated as any other type of thyrotoxicosis, with thyreostatics. If possible, the underlying amiodarone therapy should be discontinued. In contrast to the Type 1 AIT, whose basic pathophysiological substrate is the increased synthesis and release of thyroid hormones, the basis of the Type 2 AIT is a destructive thyroiditis caused by amiodarone, desethylamiodarone (DEA) as its main metabolite and an increased iodine uptake. Glucocorticoid therapy represents the basis for treatment of this type of disease.