Subclinical thyreopathies are pathological states of the thyroid gland that show no corresponding clinical symptoms, yet may be detected sporadically by laboratory examination or screening methods. They represent a novel diagnostic entity (analogous to glucose tolerance impairment--IGT or impaired fasting glycemia--IFG), which appeared due to innovations in laboratory diagnostics (sensitive TSH detection methods) and recent focus on pre-clinical stages of manifestative diseases. From a wider point of view, subclinical thyreopathies include subclinical hypothyroidism, subclinical hyperthyrodism, thyroid volume or structure changes found accidentally by sonography, initial stages of malignancy--accidental detection of a microcarcinoma and subclinical forms of thyroiditis. Controversy remains concerning exact definition, epidemiological issues, therapeutic intervention, evaluation of risk and gain implied in treatment of these borderline clinical stages and, last but not least, early screening of risk groups if necessary.