A 61-year-old woman with hypercholesterolemia, hypertension and diabetes mellitus was referred to hospital for the evaluation of chest pain at rest. Eccentric 50% stenosis in the proximal right coronary artery was detected by 64-slice multidetector row computed tomography (MDCT). The plaque morphology was considered as soft by Color Code Plaque (CCP) analysis. Seven days after MDCT, chest pain continued and transient ST-elevation was detected on the II-lead ECG monitor during echocardiography. Therefore, emergency coronary angiography was performed and confirmed the 50% stenosis as shown on MDCT. Her disease was diagnosed as vasospastic angina. For the purpose of plaque stabilization, lipid-lowering therapy with atorvastatin was instituted and her symptoms improved. After 11 months, serum total cholesterol and LDL-cholesterol levels were reduced. A second MDCT was performed and plaque morphology had changed from soft to intermediate. Cross-sectional multiplanar reconstruction of MDCT images indicated reduction of total vessel area, expansion of the lumen area and improvement of the remodeling index at the site of stenosis. The lipid-lowering therapy contributed to plaque stabilization, and CCP analysis by noninvasive MDCT was useful for plaque characterization. This case suggests that differences between vulnerable and stable plaques can be classified using MDCT to predict acute coronary syndrome.