Background: Upper abdominal surgeries have been reported to be associated with an increased incidence of postoperative atelectasis. Preventing atelectasis is important for all patients but is more important when caring for obese patients. Objectives: To determine which of the following ventilatory strategies is better in prevention of pulmonary atelectasis in obese patients undergoing non-bariatric surgery: Volume control ventilation "VC", Pressure control Ventilation "PC", Volume control ventilation + Positive End Expiratory Pressure "PEEP", Volume control ventilation + Positive End Expiratory Pressure "PEEP" + lung recruitment maneuver. Patients and methods: A randomized-controlled trial study was carried out in the operating room (OR) in Zagazig University Hospital including 92 patients. Patients were randomly allocated into four groups. G1: Volume control ventilation "VC", G2: Pressure control Ventilation "PC", G3: Volume control ventilation + Positive End Expiratory Pressure "PEEP", G4: as in G3 + lung recruitment maneuver. Results: There was significant difference between the studied groups as regards PaO 2 /FiO 2 ratio as the 4 th group was highly significant. There was also significant difference between the studied groups as regards atelectasis score with the least atelectasis score in group 4. There was a significant difference in group 4 than the other groups as regards length of stay in PACU, and need for 100% Fio2 in PACU. Finally, there was a significant difference between the studied groups as regards postoperative pulmonary complications with the 4 th group has the least postoperative complication. Conclusion:Our results suggest that volume control ventilation + Positive End Expiratory Pressure "PEEP" + lung recruitment maneuver had beneficial effects on oxygenation continued into the early recovery period and decrease pulmonary complications in the early post-operative period in obese patients undergoing non-bariatric upper abdominal surgeries.