OBJECTIVES: To evaluate the association between hypothyroidism, and the health status of older Hispanic and non-Hispanic white (NHW) men and women. To accomplish this, we determined the prevalences of the treated and untreated conditions and examined the associations between an elevated serum thyroid stimulating hormone (TSH) and cognitive and affective (mood) functions and the prevalences of symptoms and comorbidity, specifically coronary heart disease (CHD), diabetes, hypertension, and hyperlipidemia. DESIGN AND SETTING: A cross-sectional study of equal numbers of Hispanic and NHW men and women selected randomly from the Health Care Financing Administration (Medicare) rolls and recruited for a home interview followed by a 4-hour interview/examination in a senior health clinic. PARTICIPANTS: 883 volunteers, mean age 74.1 years, participated in interviews/examinations MEASUREMENTS: Serum TSH was determined in 825 participants responding to questions about thyroid replacement therapy. Serum free thyroxine (free T-4) concentrations were determined in 139 participants with elevated TSH concentrations (>4.6 mu U/mL). Symptoms, cognitive tests, a screen for depression, comorbidities (e.g., CHD), and risk factors (e.g., lipid abnormalities, diabetes, and hypertension) were compared in participants with high versus normal TSH values. RESULTS: Subclinical hypothyroidism is more common in women than in men and in non-Hispanic white women compared with Hispanic women. No differences were observed between participants with TSH elevations from 4.7 to 10 mu U/mL and those with normal TSH concentrations, and only a few differences were observed in those with TSH concentrations above 10. CONCLUSIONS: Subclinical hypothyroidism is a common condition in community-living older people, especially women. However, it appeared to have no effect on any of the measures of health status utilized until serum TSH concentrations exceeded 10 mu U/mL, and even then the effects were rarely significant.