Objective: To determine whether the inverse relation between blood pressure and all cause mortality in elderly people over 85 years of age can be explained by adjusting for health status, and to determine whether high blood pressure is a risk factor for mortality when the effects of poor health are accounted for. Design: 5 to 7 year follow up of community residents aged 85 years and older. Setting: Leiden, the Netherlands. Subjects: 835 subjects whose blood pressure was recorded between 1987 and 1989. Main outcome measure: All cause mortality. Results: An inverse relation between blood pressure and all cause mortality was observed. For diastolic blood pressure crude 5 year all cause mortality decreased from 88% (52/59) (95% confidence interval 79% to 95%) in those with diastolic blood pressures < 65 mm Hg to 59% (27/46) (44% to 72%) in those with diastolic pressures > 100 mm Hg. For systolic blood pressure crude 5 year all cause mortality decreased from 85% (95/112) (78% to 91%) in those with systolic pressures < 125 mm Hg to 59% (13/22) (38% to 78%) in those with systolic pressures > 200 mm Hg. This decrease was no longer significant after adjustment for indicators of poor health. No relation existed between blood pressure and mortality from cardiovascular causes or stroke after adjustment for age and sex, but after adjustment for age, sex, and indicators of poor health there was a positive relation between diastolic blood pressure and mortality from both cardiovascular causes and stroke. Conclusion: The inverse relation between blood pressure and all cause mortality in elderly people over 85 is associated with health status.