Prior animal model studies have demonstrated an association between telomere length and longevity. Our study examines telomere length in centenarians in good health versus poor health. Using DNA from blood lymphocytes, telomere length was measured by quantitative polymerase chain reaction in 38 sex- and age-matched centenarians (ages 97-108). "Healthy" centenarians (n = 19) with physical function in the independent range and the absence of hypertension, congestive heart failure, myocardial infarction, peripheral vascular disease, dementia, cancer, stroke, chronic obstructive pulmonary disease, and diabetes were compared to centenarians with physical function limitations and > or =2 of the above conditions (n = 19). Healthy centenarians had significantly longer telomeres than did unhealthy centenarians (p =.0475). Our study demonstrated that investigations of the association between telomere length and exceptional longevity must take into account the health status of the individuals. This raises the possibility that perhaps it is not exceptional longevity but one's function and health that may be associated with telomere length.