The surgical management of tumors of the left main bronchus withinvolvement of the lower trachea is one of the most difficult problems oftracheobronchial surgery. Two cases of adenocystic carcinoma in thislocation are presented, where resection of the tumor and reconstruction ofthe airway were performed through a left thoracotomy. In one casereconstruction of the tracheobronchial tree could be accomplished withoutloss of lung parenchyma; in the second case the left lung had to be removedsince the lobar bronchi were infiltrated by the tumor. Such extensive lefttracheobronchial resections have so far not been reported in theliterature.