Background:The aim of this study was to investigate the influence of laparoscopic and conventional open surgery on respiratory mechanics, and blood gases, and to determine convenient techniques from the point of view of intraoperative respiratory mechanics, for bariatric surgery. Method: 40 morbidly obese patients were divided into 2 groups, patients undergoing laparoscopy Group 1, and patients undergoing conventional open surgery Group 2. Resistance of airway, dynamic compliance, and peak inspiratory pressure were measured. Measurement was performed in 4 periods: a) after anesthesia induction, b) after pneumoperitoneum in the Group 1 and after incision in the Group 2, c) after gastric band placement, d) and 5 min before extubation. Blood gases were recorded concomitantly. Results: There was no significant difference between the 2 groups in values of blood gases and respiratory mechanics. Conclusion: In the morbidly obese, laparoscopic and open surgery did not cause a significant difference for respiratory mechanics when compared with each other.