Acquired adult hypothyroidism is a common disease used to be regarded as a simple condition to treat effectively due to present sensitive laboratory tests and development of medical therapy. Signs and symptoms are completely reversible. Replacement treatment of hypothyroidism is in the great majority of cases lifelong, simple and free of complications. However, there are clinical situations, where opinions of treatment are not yet unanimous and have been still developing. Classical examples are subclinical hypothyroidism, or biochemical evidence of overtreatment, as judged by a suppressed serum TSH concentration. The aim of the article is to provide with basic information on standard treatment of adult hypothyroidism and to discuss special problems and up-to-date opinions of their treatment.