Postpneumonectomy syndrome is characterized by postoperative bronchial obstruction caused by mediastinal shift. The syndrome is well documented in the medical literature as a late complication of right pneumonectomy; however, it rarely occurs following resection of the left lung, and only 10 cases have been published. The pathophysiology, clinical manifestations, prognosis, and treatment are similar for both sides of the lung. We present the case of an adult patient who underwent left pneumonectomy and developed postpneumonectomy syndrome 15 months later. Stenosis of the intermediate bronchus occurred between the vertebral body and the right pulmonary artery. Endoscopic treatment with a self-expanding metal stent was successful, and complete remission was observed over the 6 months of follow-up.