The term ‘subclinical hypothyroidism’ describes the state of slightly elevated serum TSH and normal serum free T4 and T3 levels, usually without any other clinical findings characteristic of hypothyroidism. The state is quite common in the elderly, especially in women. Subclinical hypothyroidism is most commonly an early stage of overt hypothyroidism. Progression to overt hypothyroidism ranges from 5 to 20 percent per year in patients with slightly elevated serum TSH and high thyroid antibody levels. Patients with subclinical hypothyroidism may have increased levels of are total and HDL cholesterol, which are less pronounced than in overt disease but predispose these patients to the development of severe cardiac disease. For this reason, it is necessary to consider levothyroxine therapy in some of these patients, in order to improve their quality of life and to prevent development of full-blown disease with all its sequels. Because subclinical hypothyroidism is common in the elderly (4% - 8% of people older than 60), it is necessary to establish a screening policy based on serum TSH level measurement.