The validity of coronary angioscope was discussed in several clinical settings in this article. First of all, although smooth coronary surface was observed by coronary angiography after the intervention of chronic total occlusion, protrusion or thrombus observed by angioscope occupied the arterial lumen and closed the vessel lumen. After implantation of the stent, lumen was widely opened. Serial angioscopic observation revealed that the neointima became thick and non-transparent until 6 months and then became thin and transparent by 3 years after stent implantation. These findings suggested the validity of angioscope in coronary intervention. Second, coronary angioscope revealed the morphologic and pathologic characteristics of culprit lesions in patients with acute coronary syndrome. The thrombus was observed on the yellow plaque in the culprit lesion. The thrombus formed directly over the plaque was mainly white and red thrombus might be formed after the blood flow was disturbed by the white thrombus formed by the platelet aggregation. These findings imply the importance of anti-platelet therapy after acute coronary syndromes. Finally, the angioscope can detect the minimal changes of the plaque formation, progression and rupture, that is, the entire process of the atherosclerosis. The early detection of yellow plaque might be able to intervent mechanically or pharmacologically to prevent its rupture.