Aortic complications are very rare during off-pump coronary artery bypass grafting (OPCAB). When they occur, the mortality is high. We report a case of perforation of the posterior aortic wall after punching out the hole in the ascending aorta with an automatic aortic cutter to avoid clamping for the proximal anastomosis during a routine OPCAB procedure. The consequence was a massive hemorrhage, emergency conversion to cardiopulmonary bypass and replacement of the aortic valve and of the ascending aorta.