Coronary perforation is an undesirable complication during percutaneous coronary intervention (PCI). We reviewed the cases of overt coronary perforation in our institute and analyzed their clinical backgrounds, the characteristics of the target lesion, management, and clinical outcomes. Between 1991 and 2005, we experienced 12 cases (0.35%) of coronary perforation in a total of 3415 PCI procedures. The perforation occurred during the use of debulking devices in 3 cases, immediately after stenting in 2, immediately after postdilatation of the stent in 2, and during wiring in 3 cases. Restoration was attempted by long inflation of a balloon in 7 cases, implantation of a covered stent graft in 1, and emergency surgical repair in 1 case. Subsequent cardiac tamponade occurred in 3 patients who required pericardiocentesis, and 1 patient died due to congestive heart failure. Administration of protamine was effective in stopping the bleeding in 6 patients, whereas continuation of antiplatelet therapy resulted in no overt rebleeding. Coronary perforation during PCI is a rare complication but is associated with significant morbidity and mortality. Intravenous administration of protamine is effective when it is used in conjunction with nonsurgical devices for initial management of perforation.