Forty-nine adults who had undergone cardiopulmonary bypass surgery were randomly assigned to one of three exercise programs to determine if either maximal inspiratory breathing exercises or incentive spirometry offered a therapeutic advantage over early mobilization alone. After extubation, the patients started their assigned exercise programs. A physical examination and pulmonary function tests were performed preoperatively, at the start of the exercise program, and 24 and 48 hours after the start of the program. The results showed a significant decrease (approximately 50%) in lung volumes but no airflow obstruction in patients who had coronary artery bypass graft. In those patients who had valve replacement, lung volumes fell, and in addition, mild airflow obstruction occurred. A majority of patients had postoperative pulmonary complications. There were no significant differences among the exercise programs in improving lung volumes and airflow or in preventing postoperative complications. We conclude that maximal inspiratory breathing exercises or incentive spirometry, when used in addition to early mobilization, offers no therapeutic advantage over early mobilization alone after cardiopulmonary bypass surgery.