A 74-year-old female developed aortocoronary dissection during percutaneous coronary intervention. The forceful manipulation of the guide catheter and contrast medium injection seemed to be the cause of the aortocoronary dissection involving the coronary sinus of Valsalva. The entry of the dissection was closed with subsequent obliteration of the false lumen by coronary stenting under the guidance of intracoronary ultrasonography and angiography.