Controversy exists regarding the routine use of breathing exercises in the prevention of pulmonary complications after upper abdominal surgery. We prospectively randomized 153 patients who had noncompromised pulmonary status; the control group (84 patients) engaged in no breathing exercises, and the respiratory therapy group (69 patients) engaged in preoperative and postoperative breathing exercises supervised by the physical therapist. Postoperative pulmonary complications were classified using criteria derived from chest roentgenograms, arterial blood gas samples, and temperature registration. The incidences of postoperative complications in the treatment group and in the control groups were 19% and 60%, respectively. In the present study, preoperative lung function tests had no additional or predictive value. We advise preoperative and postoperative breathing exercises as a prophylactic treatment in all patients scheduled for upper abdominal surgery.