Renin-angiotensin system is well known that it plays an important role in the initiation and amplification of atherosclerosis that lead to cardiovascular disease. Angiotensin II is deeply involved in vasoconstriction, oxidative stress, inflammation, thrombosis, vascular remodeling, and sympathetic nerve activity. Many studies have documented the favorable effects of angiotensin converting enzyme inhibitor(ACE-I) and angiotensin receptor blocker(ARB) on cardiovascular disease in basic and clinical trials. Now accumulated evidences suggest ACE-I and ARB potentially prevent coronary plaque rapture, thrombosis and myocardial remodeling with acute coronary syndrome (ACS). ACS is occurred from plaque rupture on mild to moderate coronary atherosclerosis. Therefore, on treatment of ACS, it is important to prevent the plaque rupture and thrombosis by pharmacological intervention with ACE-I and ARB than coronary artery intervention which is down stream therapy for coronary artery stenosis.