Aging is associated with a host of alterations in thyroid gland structure and function. Some of these changes have favorable effects on longevity, whereas others are maladaptive and contribute to a decline in health and quality of life. An area of particular controversy is the diagnosis and management of subclinical hypothyroidism in the elderly. The clinical diagnosis of hypothyroidism in the elderly is difficult, because many signs and symptoms associated with hypothyroidism are commonly present in euthyroid elderly individuals. The biochemical profile of subclinical hypothyroidism includes normal serum levels of thyroid hormones with mildly elevated serum thyrotropin concentrations in the range of 4.5 to 10 mIU/L. In this article, the epidemiology of subclinical hypothyroidism in the elderly is reviewed, the potential advantages of mild hypothyroidism in people over the age of 75 years are discussed, and some guidelines for screening and management of this common thyroid dysfunction are suggested.