The study subjects (men or women, 25 to 70 years of age) will be divided into two groups. Individuals with pre-hypertension (blood pressure = 120-139/85-90 mmHg) will be double-blindly allocated to either losartan or hydrochlorothiazide therapy respectively in groups 1 and 2. Study subjects will be assessed for their compatibility with inclusion and exclusion criteria, and subjects meeting the criteria will undergo baseline biopsies of gluteal subcutaneous resistance vessels. In addition, stiffness of aorta (carotid-femoral pulse wave velocity) and finger endothelium-dependent hyperemic responses will be evaluated. Subjects in each treatment group will receive antihypertensive therapy for 6 months, to control their blood pressure to 100-120/70-80 mmHg, and then have repeat gluteal biopsies, aortic stiffness and endothelial function measurements. The media/lumen ratio of resistance arteries 150-300 um in lumen diameter in the biopsied tissues will be determined. Previous work (1-3) has shown this parameter to be a useful marker of hypertensive vascular disease which may be modified by treatment with antihypertensive agents, particularly blockers of the renin-angiotensin system.