A 58-year-old man underwent cardiac catheterization for unstable angina. The coronary angiogram revealed severe stenosis of the right coronary artery. Although 20-MHz, phased-array intravascular ultrasound (IVUS) only visualized eccentric, low echoic plaque at the culprit site, optical coherence tomography (OCT) clearly revealed ruptured plaque and an intraluminal thrombus. OCT also revealed a small ruptured plaque and an eroded plaque with intraluminal thrombi in a distal site remote from the culprit lesion, neither of which was visualized by IVUS.