Background: Morbidly obese patients have high risk to develop postoperative pulmonary complications, 80% of them have obstructive sleep apnea and obesity hypoventilation syndrome. Patients with sleep breathing issues often use continuous positive airway pressure (CPAP) machines, which employ mild air pressure to keep the airways open. Incentive spirometry encourages cases to take slow, deep breaths, triggering natural sighs. Aim: to compare preoperative CPAP and incentive spirometer on postoperative pulmonary complications incidence in morbidly obese cases post laparoscopic bariatric surgeries. Patients and method: 52 morbidly obese patients underwent general anesthesia for laparoscopic bariatric surgery were randomly allocated either received CPAP or incentive spirometry before the day of surgery, patients were assessed for postoperative pulmonary complications, changes in pulmonary function, lung mechanics and postoperative hypoxia incidence.Results: there was no significant change among both groups in the context of postoperative respiratory complications: atelectasis was the most common complications (61.5% and 46.2% in CPAP and spirometry respectively). Better postoperative pulmonary function profile and lung mechanics was noted in spirometry group. Conclusion: Preoperative application of CPAP and incentive spirometer have comparable result as regard incidence of postoperative pulmonary complications. However, incentive spirometer improves intraoperative lung mechanics and postoperative pulmonary functions.