Laparoscopic procedures are accompanied by an increased intra-abdominal pressure and diaphragmatic elevation, which may interfere with adequate ventilation in obese patients. Re-expansion of a collapsed lung could be followed by pulmonary edema. Here, we describe a case of re-expansion pulmonary edema after laparoscopic bariatric surgery. A 23-year-old-female with morbid obesity received general anesthesia for laparoscopic adjustable gastric banding surgery. Unintentional one lung ventilation occurred for a short period during the operation and was promptly corrected. At the end of the operation, as spontaneous respiration recovered, profuse pinkish frothy sputum emerged from the endotracheal tube. Diffuse patchy increased opacity on the left lung field was observed by chest X-ray. With aspiration of bronchial secretion and oxygen supplementation, the patient was recovered uneventfully. We presume that inadequate lung expansion during pneumoperitoneum and unintentional right endobronchial intubation caused atelectasis of the left lung, and induced re-expansion pulmonary edema at the end of the operation. This case emphasizes the importance of constant vigilance with respect to endotracheal tube position and ventilation during laparoscopic surgery in obese patients.