Aortic dissection in cardiac allograft recipients has not been reported previously, to our knowledge. We have observed two fatal aortic dissections in heart transplant recipients: one in the immediate postoperative period and one occurring 5 years after transplantation. We discuss the clinical presentations, pathologic findings, possible pathogenetic mechanisms, and risk factors. Because the frequency of aortic dissection after heart transplantation appears to be relatively low (< 1%), such disease may be clinically unsuspected. Given the uniformly poor outcome observed in our two patients, we suggest that increased awareness of the possible development of aortic dissection after heart transplantation may result in improved survival of affected patients.