Abstract--In people aged >80 years, the so-called very elderly, there is uncertainty about the relation between hypertension and cardiovascular morbidity. The aims of this study were to investigate whether hypertension in people aged >80 years is associated with target-organ damage, over and above the effects of age, and to determine whether ambulatory blood pressure monitoring (ABPM) could improve on conventional blood pressure monitoring (CBPM) in predicting target-organ damage. Investigations included echocardiographic measurement of left ventricular mass index (LVMI), brain magnetic resonance imaging assessment of periventricular hyperintensity (PVH), urinary albumin-creatinine ratio (ACR), aortic pulse wave velocity (PWV), and 24-hour ABPM. Forty-three subjects, at a mean age 84.3 years, were studied, 22 normotensive (NT) and 21 hypertensive (HT). CBP was 184/89 and 145/76 mm Hg in the HT and NT groups, respectively. In men, LVMI was significantly greater in HT subjects, 157±37 vs 123±15 g/m² in NT subjects (P<0.05). In women, LVMI was similar in both groups. Urinary ACR was greater in HT than in NT subjects (log ACR, 1.21±0.50 vs 0.95±0.23; P<0.05). Cerebral PVH grade was higher in the HT subjects (2.6±0.8 vs 2.2±0.9), although this difference was not significant. Aortic PWV did not differ between the 2 groups. ABPM was positively associated with urinary ACR and cerebral PVH, independent of its correlation with CBPM. In advanced old age, HT is associated with evidence of target-organ damage. ABPM can improve on CBPM in predicting very elderly subjects with HT target-organ damage.