The consequences of hypertension and its treatment differ in very old men and women compared to younger populations. In populations aged 85 years and older, higher levels of systolic and diastolic blood pressures are associated with increased survival, and this relationship is not eliminated by controlling for comorbidity, blood pressure treatment, and other relevant factors. In addition, in 3 of the 4 published randomized controlled trials of treatment of hypertension that included subjects aged 80 years or older, the investigators reported loss of efficacy of treatment in preventing the primary end points in subjects aged 80 and older. In a meta-analysis of those trials, total mortality was actually 14% higher (p =.05) in the treatment group for subjects aged 80 years and older. These data suggest 2 conclusions. First, we should reexamine that dictum that nontreatment of hypertension in those aged 80 years and older is de facto evidence of "ageism." Second, we are unlikely to come to any set of coherent "rules" regarding treatment of hypertension (and several other conditions) in the very old until we routinely stratify all older subjects enrolled in interventional or observational trials by indicators of physiologic vigor.