Pulmonary complications represent the leading cause of postoperative morbidity. Thoracic surgical procedures carry the highest risk of such complications. Prevention of pulmonary morbidity in thoracic surgical patients depends on an understanding of expected pulmonary pathophysiologic changes, preoperative assessment of patient risk, and specific interventions aimed at minimizing the incidence and severity of these complications. This article reviews these strategies and gives recommendations concerning the use of preoperative evaluation and postoperative lung expansion techniques.