Preoperative pulmonary evaluation and preparation involve first identifying patients at risk for complications and then attempting to modify that risk. For most patients without underlying lung disease, a thorough history and physical examination and preoperative instruction in the use of incentive spirometry is sufficient. In patients with known or suspected lung disease, preoperative pulmonary function tests, while unproven as prognostic tools, may reduce risk by aiding in medical management, and in the case of the lung resection candidate, by helping determine very directly his or her viability for the procedure.