This study was designed to investigate the frequency and diagnostic importance of the pleuropulmonary manifestations of the postcardiac injury syndrome. A retrospective study of 35 patients (2 to 76 years old) with clearly defined postcardiac injury syndrome is presented. Twenty-one cases followed cardiac surgery, and 14 appeared after myocardial infarction. The onset of the syndrome was an average of 20 days following injury. The major clinical findings were pleurisy (91 percent; 32/35), fever (66 percent; 23/35), pericardial rub (63 percent; 22/35), dyspnea (57 percent; 20/35), rales (51 percent; 18/35), pleural rub (46 percent; 16/35), elevated erythrocyte sedimentation rate (96 percent; 25/26), and leukocytosis (49 percent; 17/35). The chest roentgenogram was abnormal in 94 percent (33/35). Pleural effusion was present in 83 percent (29/35), parenchymal infiltrates in 74 percent (26/35), and an enlarged cardiac silhouette in 49 percent (17/35). Analysis of pleural fluid was performed on 16 samples from 12 patients and revealed a bloody exudate with a pH greater than 7.40. The data presented document that pleuropulmonary involvement is a common manifestation of postcardiac injury syndrome. In addition, we discuss how these findings can be used to differentiate this syndrome from other clinical entities that may appear following cardiac injury, ie, parapneumonic effusions, congestive heart failure, and pulmonary embolism.