Hyperlipidemia is one of the major coronary risk factors, which leading to the clinical worse outcome in patients with coronary artery disease, that is, acute coronary syndrome. Coronary plaque rupture followed by the formation of thrombus has been revealed to be a major cause of acute coronary syndrome. It would be important to detect the vulnerable plaque before its rupture, but there were no ways to detect by the conventional methods except coronary angioscopy. Yellow plaque and thrombus are mostly observed at the culprit lesion by the coronary angioscopy, which suggests that vulnerable plaque is dark yellow. Coronary angioscopy may diagnose the high-risk group among patients with hyperlipidemia.