There is limited information concerning the current practice of intraoperative mechanical ventilation in obese patients, and the optimal ventilator settings for these patients are debated. The authors investigated intraoperative ventilation parameters and their associations with the development of postoperative pulmonary complications in 2,012 obese patients. Results: Obese patients are frequently ventilated with high tidal volume and low PEEP, and seldom receive recruitment maneuvers. Postoperative pulmonary complications increase hospital stay, and are associated with preoperative conditions, duration of anesthesia and intraoperative ventilation settings. Randomized trials are warranted to clarify the role of different ventilatory parameters in obese patients.