A patient with recent onset of unstable angina was found to have a severe, eccentric stenosis of the proximal left anterior descending coronary artery. Rotational atherectomy was performed. After the first passage of the burr across the stenosis, an intraplaque crater was angiographically visualized. It is hypothesized that the patient's clinical presentation may be attributed to plaque rupture and formation of an intraplaque crater which was sealed by a fibrous cap. This cap was "shaved" by the rotating burr, exposing the crater. Adjunctive balloon dilatation expanded the true lumen and compressed the crater.