An 84-year-old man presented with acute dyspnea and chest pain attributed to his long medical history of cardiorespiratory problems. Admission chest roentgenogram revealed a moderate pneumopericardium and a cavitary lesion in the base of the right lung. The lesion was found to be a bronchogenic carcinoma perforating through the upper pericardium to form a bronchopericardial fistula, confirmed by autopsy. A review of the literature concerning the various causes of pneumopericardium, the clinical features and the principles of treatment is included.