Successful pneumonectomy in humans was preceded by the development of techniques for lobectomy. If experience in the animal laboratory had not been ignored, fears regarding sudden occlusion of the pulmonary artery and the fate of the postpneumonectomy pleural space would have been allayed. Precise hilar dissection was facilitated by the development of endotracheal anesthesia, which had been used successfully in animal experiments for at least half a century.