During one year five patients were observed with the adult respiratory distress syndrome who were found at necropsy to have cavitated lung infarcts following bland (non-infected) pulmonary thromboembolism. There were three instances of bronchopleural fistula and in one person a tension pneumothorax was the immediate cause of death. Four of the five patients had severe lung infections. In all patients airway pressure was raised as a result of positive pressure mechanical ventilation. It is postulated that diffuse microvascular injury, bacterial pneumonia, and high airway pressures may be important factors predisposing patients with adult respiratory distress syndrome to develop lung necrosis, cavitation, and bronchopleural fistula after bland pulmonary thromboembolism. This complication may occur more frequently than has been previously recognised.