A polytetrafluoroethylene (PTFE)-covered stent is specially used to treat coronary perforation complicating percutaneous intervention in order to prevent the aneurysm from rupturing, but until now it has not been known if endothelialization occurs inside this type of stent. A patient with a giant aneurysm of the right coronary artery underwent successful implantation of a PTFE-covered stent. Angiography at 9-month follow-up showed focal restenosis at the proximal edge of the stent and coronary angioscopy revealed restenosis as a result of thrombus formation. Absence of endothelialization in the covered stent was also detected by angioscopy and optical coherence tomography. These findings suggest that in-stent thrombosis must be prevented after PTFE-covered stent implantation.