We describe an unusual presentation of a case of fulminant unilateral pulmonary edema caused by unrecognized right endobronchial intubation that occurred during patient movement at the end of surgery. We review factors which may predispose to this complication. During emergence from anesthesia at the conclusion of bariatric surgery, a 27-yr-old patient (163 kg, body mass index 61.5 kg.m(-2)) became hypoxemic despite vigorous spontaneous ventilatory efforts through a 7.0 mm endotracheal tube with 100% oxygen. Right mainstem endobronchial tube malposition was detected by auscultation. The tube was repositioned, followed by copious pink frothy pulmonary edema abruptly issuing from the tracheal tube. Chest radiography revealed dense left lung infiltrates, consistent with unilateral negative pressure pulmonary edema, caused by brief, but forceful, inspiratory efforts against an obstructed left bronchus. This condition resolved over the following 24 hr. The patient's trachea was then extubated, and the remainder of her recovery was unremarkable. A high degree of airway anatomic variation, common tracheal tube insertion practices, unreliability of tube position detection methods, and the effects of patient positioning may all contribute to endotracheal tube malposition, including partial endobronchial intubation. Several modifications in airway management may help to prevent such complications of tracheal tube malposition.