Objective: In patients with obesity, use of positive end-expiratory pressure (PEEP) > 5 cm H 2 O (centimeters of water) has been shown to prevent intraoperative atelectasis. This study compares the rate of postoperative pulmonary complications (PPCs) associated with PEEP > 5 cm H 2 O and PEEP ≤ 5 cm H 2 O in patients with obesity who underwent surgery under general anesthesia with mechanical ventilation.Methods: This study searched Medline, Embase, the Cochrane Central Register of Controlled Trials (CENTRAL), and the Cumulative Index to Nursing and Allied Health Literature (CINAHL) using the terms "PEEP," "anesthesia," and "ventilation."Cochrane ReviewManager (RevMan) version 5 was used for data analysis. The primary outcome was a composite of PPCs, including atelectasis, pneumonia, pneumothorax, and acute respiratory failure. Results:The initial search identified 903 titles and abstracts, and 4 randomized controlled trials were included for analysis. We included a total of 2116 participants from four randomized controlled trials that compared PEEP ≤ 5 cm H 2 O with PEEP > 5 cm H 2 O in adult patients with obesity. There was no statistically significant difference in PPCs between the PEEP ≤ 5 cm H 2 O and PEEP > 5 cm H 2 O groups (risk ratio = 2.21, 95% CI: 0.41-11.83; p = 0.35). However, a significant heterogeneity was found within included studies (I 2 = 53%).Conclusions: It is unclear whether PEEP > 5 cm H 2 O improves the postoperative clinical outcome in patients with obesity, which is in contrast to previously established evidence that it reduces atelectasis in patients with obesity.