Anomalous coronary arteries with origins from the contralateral aortic sinus and coursing between the aorta and pulmonary trunk have received much attention because of their association with sudden death. These morphologic features have not been well assessed in vivo. The investigators describe 3 cases of anomalous right coronary arteries arising from the left coronary sinus with intravascular ultrasound findings. In the present patients, characteristic vessel distortion was consistently observed at the ostium of the anomalous right coronary arteries, as well as systolic compression of the intra-arterial segments. In conclusion, the slitlike ostium might be associated with the higher incidence of sudden death under strenuous exercise and exercise-induced myocardial ischemia.