J. R., a 19-year-old white male farmer, was first seen on June 7, 1954, for complaints including weakness, anorexia, and loss of 35 lbs. weight since March, 1954. Although a recent posterioanterior chest film had been reported as normal, chest x-ray film was repeated, revealing a large round tumor mass with small nodular extensions (Fig. 1), all of which had been previously hidden by the cardiac shadow. A left lateral x-ray film of the chest localized this mass in the left lower lobe behind the heart. The patient suddenly became dyspneic and developed signs and symptoms of severe internal hemorrhage. X-ray films now showed the left hemithorax to be opaquely blurred with some shift of the mediastinum to the right (Fig. 2). Closed (water-sealed) drainage through catheters introduced intercostally resulted in escape of considerable bloody fluid. X-ray film showed opacity of the lower two-thirds of the left lung field with some improvement in the position of the mediastinum, but dyspnea, requiring the administration of oxygen through an intranasal catheter continued. He was given whole blood transfusions and his blood pressure maintained at 120/80. He was started on penicillin, and his oral temperature of 104#{176} fell over a period of a few days to 101#{176}. His pulse rate fell from 150 to 120 per minute. He was unable to void voluntarily (necessitating an indwelling Foley catheter), sweated profusely and complained of dyspnea, weakness and chest and back pain. Bronchoscopy and studies of the bronchial secretions for malignancy were negative. On June 29, 1954, operation was performed through a standard left thoracotomy incision. The pleural space was filled with an extensive blood clot and some free bloody fluid. Almost as soon as removal of this blood clot was undertaken, the anesthetist reported that free bloody fluid was filling and escaping out of the endotracheal tube. The operator (A.M.T.) introduced his hand blindly through the extensive blood clot to the upper hilar region and compressed the left main stem bronchus there, later applying a Satinsky clamp to this region. The anesthetist was then able to clear the tracheobronchial tree and maintain a satisfactory anesthetic for the remainder of the operation.