A 47-year-old man was admitted to the emergency room in November 1994 with left-sided chest pain. Two days before admission, he had fallen two meters and hit the left side of his chest. A chest roentgenogram showed patchy infiltrative shadows and a pleural effusion confined to the right lung field. Bloody fluid was obtained from the right B3b by bronchoalveolar lavage. Specimens obtained from the right lung by transbronchial lung biopsy revealed deposition of hemosiderin and precipitation of fibrin, which were consistent with lung contusion. The abnormal shadows on the chest roentgenogram disappeared spontaneously within one week. Review of the literature suggests that contra coup pulmonary contusion is rare, and that the mechanism might involve injury of small vessels by high-speed vibration of the contralateral part of the mediastinum.