Neoplasms of the left upper lobe may spread directly to the anterior mediastinal group of nodes without involving the inferior tracheobronchial, superior tracheobronchial, or paratracheal nodal chain. Routine cervical mediastinoscopy does not sample the anterior mediastinal node group. Parasternal anterior mediastinotomy was performed in 28 patients with left upper lobe carcinoma and normal findings from cervical mediastinoscopy. Despite the normal findings at cervical mediastinoscopy, 10 of the 28 patients were deemed to have inoperable disease because of spread of the neoplasm to the anterior nodal group or because of direct neoplastic involvement of the aorta or main pulmonary artery. All patients in whom results of anterior mediastinotomy were normal had resectable lesions at thoracotomy. Fourteen of the 16 patients who came to thoracotomy had normal hilar nodes. Parasternal anterior mediastinotomy, introduced by Chamberlain, should be performed in addition to standard cervical mediastinoscopy if the nodal drainage of left upper lobe neoplasms is to be more completely evaluated. Combining these two procedures samples all major drainage pathways except the posterior mediastinal nodal chain.