Purpose: Disruption of coronary artery plaque is the primary cause of acute coronary syndrome(ACS). The vulnerable, rupture-prone plaques are characterized by large lipid cores with thin fibrous caps, positive remodeling, and small coronary calcium. Recently, multidetector computed tomography (MDCT) has been known to characterize the coronary artery plaques. We studied the difference of culprit lesions between ACS and stable angina pectoris(SAP) using multidetector computed tomography(MDCT) Methods: 64-slice MDCT was conducted on 59 patients with 26 patients with ACS and 33 patients with SA before percutaneous coronary intervention (PCI). The culprit coronary lesions were evaluated for signal intensity (SI) of plaque presenting as Hounsfield unit (HU), spotty calcification, outer vessel diameter and area in culprit and reference lesion. The remodeling index (RI) was defined as the ratio of lesion diameter and mean of proximal and distal reference diameter. Results: In patients with ACS, culprit coronary lesions had significantly higher RI than patients with SAP (1.14짹1.19 vs 0.91짹0.30, p=0.001). The plaque of culprit coronary lesions in patients with ACS were less calcified (3.8% vs 36.4%, p=0.008). The mean SI of plaques was significantly lower in ACS patients (38.39짹22.35HU vs 89.16짹43.45HU, p=0.000) In addition, more spotty calcification were observed in patients with ACS (93.8% vs 23.8%, p=0.001). Conclusions: In our study, the culprit lesions of ACS had higher RI, lower SI of plaque and more spotty calcification than the lesions of SAP.