Continuous positive airway pressure (CPAP) is used to prevent apneic arrest and/or hypoxia in patients suffering from obstructive sleep apnea. This modality has not been universally accepted for patients following upper gastrointestinal surgery because of concerns that pressurized air will inflate the stomach and proximal intestine, resulting in anastomotic disruption. This study was performed to assess the safety and efficacy of postoperative CPAP for patients undergoing a gastrojejunostomy as part of a Roux-en-Y gastric bypass (RYGB) procedure. A total of 1067 patients (837 women [78%] and 230 men [22%]) were prospectively evaluated for the risk of developing anastomotic leaks and pulmonary complications after the RYGB procedure. Of the 1067 patients undergoing gastric bypass, 420 had obstructive sleep apnea and 159 were dependent on CPAP. There were 15 major anastomotic leaks, two of which occurred in CPAP-treated patients. Contingency table analysis demonstrated that there was no correlation between CPAP utilization and the incidence of major anastomotic leakage (P= 0.6). Notably, no episodes of pneumonia were diagnosed in either group. Despite the theoretical risk of anastomotic injury from pressurized air delivered by CPAP, no anastomotic leaks occurred that were attributable to CPAP. There were no pulmonary complications in a patient population that is at risk for developing them postoperatively. CPAP is a useful modality for treating hypoventilation after RYGB without increasing the risk of developing postoperative anastomotic leaks.