The results of a clinically performed preoperative stair climb was compared to the presence of postthoracotomy complications in the retrospective hospital record review of 54 adult men. The stair climb was a maximum of five flights (125 steps) performed at the patient's rate and terminated at his request. Pulmonary function measurements and facets of the stair climb physiology were also examined in reference to the presence, type, and severity of complications experienced. Most minor complications such as transient arrhythmias, atelectasis, and pneumonia were clearly not predicted by the stair climb performance. The ability to climb three flights preoperatively most clearly separated those patients having the longer postoperative intubation and hospital stay, greater frequency of complications, and cumulative complication score (p less than 0.005). This retrospective study did not have sufficient numbers of fatal cardiopulmonary complications to exclude the possibility that these may be predicted by the results of this simple test.