An unusual case of Herpes simplex virus (HSV) pneumonia in a heart transplant recipient receiving chronic immunosuppressive therapy is reported. This infection presented an indolent course manifested by a chronic left pulmonary infiltrate unresponsive to antibiotic therapy and mild hypoxemia. Death eventually occurred as a consequence of an other infectious complication of the postoperative period. The HSV etiology of the necrotizing pneumonia observed at autopsy was established on the basis of histologic findings.