Pathologically, the lesions responsible for acute coronary syndrome (ACS) are ruptures of vulnerable plaques (and occasionally fibrous-cap erosions or calcified nodules) with a superimposed thrombosis. We aimed to clarify the clinical presentations related to the morphologies of coronary lesions of ACS using intravascular ultrasound (IVUS) and optical coherence tomography (OCT).Seventy-five culprit lesions of ACS patients were clearly assessed with IVUS and OCT. Patients were classified into two groups based on the presence or absence of a rupture of a culprit plaque as identified by OCT. Clinical characteristics and lesion morphologies were compared between the two groups. Waist circumference was significantly greater (p<0.02) and prevalence of the metabolic syndrome (MS) higher (p=0.0011) in the rupture group. The prevalence of prodromal angina was higher in patients without plaque ruptures (p<0.0001). Using multivariate analysis, the MS and prodromal angina were independent predictors of rupture of a culprit coronary plaque (odds ratio (OR): 27.30, p<0.003 and OR: 0.04, p=0.0004, respectively). Among the components of the MS, the prevalence of abdominal obesity was a significant independent predictor of rupture of a culprit plaque (OR: 4.24, p<0.02).There are two presentations related to the coronary lesion morphologies of ACS: we should understand these aspects of ACS.