Autosomal Dominant Polycystic Kidney Disease (ADPKD) is the most common genetic renal disease and is the third most common cause of renal failure in this country. In ADPKD cysts grow in the kidneys over time due to cyst development and expansion. Early ADPKD patients develop hypertension which is associated with a faster rate of progression to renal failure. To date no effective therapy has been developed for patients with hypertension and ADPKD that slow progression of disease. Activation of the reninangeotensin- aldosterone system is associated with hypertension in ADPKD. There are now two classes of antihypertensive medications which inhibit the activation of this system. These include Angiotensin Converting Enzyme Inhibitors (ACEI) and Angiotensin Receptor Blocking Agents (ARB). It is not known whether combining these agents together will be effective in slowing progression of renal failure in ADPKD and if levels of blood pressure control are important in slowing progression of renal failure. HALT is a prospective longitudinal randomized double blinded study will be performed in 1018 subjects at 7 clinical sites over a period of four years. There will be 254 subjects studied at Emory University involving two patient populations. Study A will involve subjects'age 17-45 years with normal renal function (estimated GFR >60 ml/min) and the rate of change in renal size measured by magnetic resonance imaging (MRI) will be determined. Subjects will also be separated into two levels of blood pressure control, <110/75 (rigorous control) or <130/80 mm Hg (standard control). In study Group B, subjects'age 18-64 years with less than normal renal function (estimated GFR 25-60 ml/min) will be treated to the same level of blood pressure level (<130/80 mm Hg). The composite primary end point for Study B includes time to doubling of serum creatinine concentration, renal replacement therapy or death. All eligible subjects will undergo washout from their antihypertensive medications, undergo a baseline evaluation, followed by a dose titration phase and a maintenance phase for the duration of the study. This study will determine the efficacy of dual inhibition of the RAAS as well as rigorous blood pressure control in preventing progression of renal disease in ADPKD.