We believe that an azygos fissure may predispose to bleeding during thoracoscopic surgery. An azygos fissure causes important morphologic changes in the superior mediastinum and thereby poses a risk of massive bleeding during thoracoscopic procedures. We report on a successful thoracoscopic procedure conducted in a patient with palmar hyperhidrosis and an azygos fissure and emphasize that the course of the thoracic sympathetic chain runs laterally along the base of the azygos fissure.