Subclinical thyroid disease is a common finding on testing of thyroid function and its management remains controversial.Epidemiological data from large population studies from USA and Europe.There is an increased risk of progression to overt hypothyroidism or hyperthyroidism. The treatment of mild thyroid failure is of importance in optimizing pregnancy outcome.Diagnostic criteria differ and there is variation between management guidelines. The difference was found in long-term clinical outcomes between endogenous and exogenous subclinical hyperthyroidism.Meta-analyses have provided epidemiological data in cardiovascular mortality and morbidity in subclinical thyroid disease. Increased use of echocardiography and bone markers in identifying those who benefit from intervention.A randomized controlled trial to identify those subjects identified from screening programmes that benefit from intervention in terms of morbidity and mortality.