In middle-age, level of blood pressure (BP) is a strong and independent predictor of both total and cardiovascular disease (CVD) mortality. However, among the elderly, recent short-term observational studies, including the East Boston Established Populations for Epidemiologic Studies in the Elderly (EPESE), have raised the possibility of a J-shaped curve. In a study of short-term mortality, low blood pressures were positively associated with total and cardiovascular disease mortality. However, a further analysis confined to the 2079 (68 percent) of this cohort who were also screened nine years previously for the Hypertension Detection and Follow-Up Program showed the more conventional positive linear relationship between systolic blood pressure, and no association between diastolic blood pressure and mortality. The observations of higher short-term total and cardiovascular disease mortality at lower blood pressure levels among the elderly could have reflected a particular susceptibility to deleterious consequences of drug therapy for high blood pressure. Alternatively, such a finding might have been artifactual, due to survival bias or confounding by co-morbid conditions.