The issue of how far blood pressure (BP) should be lowered to achieve the greatest reduction in the risk of cardiovascular disease has been a matter of scientific debate. Although a few trials tried to answer this question, they failed to convincingly show the optimal target BP level, in part because of poor reproducibility and wide variability of conventional casual BP measurement used in these trials. On the other hand, in Japan, calcium antagonist (Ca-A) and angiotensin converting enzyme inhibitor (ACE-I) have been two major medications of initial therapy for hypertension, while angiotensin II receptor antagonist (ARB), which has recently been introduced, is also used now widely as an initial therapy. However, no large-scale interventional trial has been conducted to show which of these three initial medication can give the greatest benefit in terms of reduced cardiovascular disease risk in the Japanese hypertensive patients.