Intravascular ultrasound (IVUS) is a safe, accurate, and reproducible method of detecting vessel wall structure and disease. In this case, we describe a 75-year-old female with hypertension and effort angina. Coronary arteriography revealed critical stenosis in the distal right coronary artery (RCA), and intravascular ultrasound (IVUS) demonstrated spontaneous dissection flap. A significant dissection-like lesion developed at the distal part of the lesion after ballooning and stenting. Another stent was used to cover the edge dissection. The dissection-like lesion extended proximally and distally and was complicated with inferior wall myocardial infarction. IVUS revealed coronary mural hematoma which compromised the vessel lumen. We used stents to maintain adequate coronary lumen and flow. One week later, follow-up angiography demonstrated patent RCA. The patient was discharged and has had no symptom until now. Using angiography, it is difficult to differentiate coronary mural hematoma from dissection. IVUS can provide valuable information in this situation.