Vigorous respiratory therapy can prevent the development of postoperative pulmonary complications which occur with increased frequency after upper abdominal surgery. Obesity poses an additional risk factor. To study the effects of postoperative chest percussion with postural drainage (CPT), 53 consecutive patients undergoing Roux-en-Y gastric stapling procedures for treatment of morbid obesity were randomized to two groups. Both received identical postoperative respiratory care, except the study group received additional CPT. It was concluded that the addition of CPT to patients without prior chronic lung disease undergoing upper abdominal surgery caused patient discomfort, increased hospital cost, and failed to affect the incidence of postoperative pulmonary complications.