Anatomical variations in the pulmonary vessels present a potential risk for intraoperative bleeding and damage to the pulmonary circulation during pulmonary resection. Here, we present a patient who underwent left upper lobectomy for lung cancer. The patient had a dangerous mediastinal basal pulmonary artery variation that could be mistaken for the mediastinal lingular pulmonary artery and be divided during left upper lobectomy. (c) 2011 Published by European Association for Cardio-Thoracic Surgery. All rights reserved.