To evaluate the relationship between blood pressure control and the progression of brain atrophy in the elderly, patients with essential hypertension and brain atrophy were longitudinally evaluated using computerized tomography (CT) . The study evaluated 48 patients with essential hypertension aged 46-78 years, and 30 sex- and age-matched normotensive control subjects. The extent of brain atrophy as determined by caudate head index (CHI) , the inverse cella media index (iCMI), and Evans'ratio (ER) was estimated twice at an interval of 5-9 years (mean, 6.9 years). The mean annual increases in CHI (ΔCHI), iCMI (ΔiCMI), and ER (ΔER) were evaluated. Mean blood volume in the common carotid artery (BF) and the decrease in BF per year (ΔBF) were also determined. The ΔCHI, ΔiCMI, and ΔER increased with age in the hypertensive subjects as well as the control group across all age groups evaluated. The ΔCHI, ΔiCMI, and ΔER were significantly greater in the patients with essential hypertension in their 50 s as compared with the controls. In patients with essential hypertension aged 65 years or older, the ΔCHI, ΔiCMI, and ΔER were significantly lower in the group in whom the blood pressure was controlled within the range of borderline hypertension than the groups in which it was controlled in the range of normal or mild hypertension. In the younger patients under the age of 65 with essential hypertension, blood pressure control did not affect the ΔCHI, ΔiCMI, and ΔER. The ΔCHI, ΔiCMI, and ΔER were significantly correlated with ΔBF in both groups. These findings indicate that control of systolic blood pressure within the range of borderline hypertension may delay the progression of brain atrophy in elderly patients with essential hypertension. (Jpn Circ J 1999; 63: 79 - 84)