The purpose of preoperative pulmonary assessment is to predict which patients are at greater risk of pulmonary complications, under which circumstances such complications may occur, and whether surgery should be denied based on that risk. In this article, the author addresses the following major issues in preoperative pulmonary assessment: 1) the risk of pulmonary complications in relation to the type of surgical procedure; 2) the value of preoperative pulmonary function testing, including when such testing should be performed and how the results should be used; and 3) guidelines for assessment of those patients about to undergo resectional surgery of the lung.