We report a case of bacterial endocarditis in a heart transplant recipient that was diagnosed 6 weeks after operation when a transesophageal echocardiogram revealed vegetations on both sides of the atrial septum. The patient also had postoperative mediastinitis and pericarditis. He underwent two mediastinal explorations, pericardiectomy, and 22 weeks of antibiotics and is free of infection 1 year after transplantation. We presume that the source of infection was contamination of the donor heart by the donor's right lung, which was harvested en bloc with the heart.