This paper describes the clinical management of patients with malignant cells in their sputum and a normal chest roentgenogram and those with asymptomatic peripheral pulmonary masses. The source of malignant cells in the sputum of patients with no roentgenographic abnormalities can be localized by tantalum bronchography and fiberoptic bronchoscopy. Peripheral pulmonary masses can be diagnosed preoperatively by needle biopsy or transbronchial fiberoptic bronchoscopy with little morbidity and no mortality. These procedures are not necessary, however, if there is firm clinical and roentgenographic evidence of malignancy. Bronchogenic carcinomas presenting as asymptomatic circumscribed peripheral pulmonary masses have a 25% incidence of occult mediastinal lymph node metastases. In view of this relatively high incidence of metastasis, we think mediastinoscopy should routinely be performed prior to thoracotomy is asymptomatic patients with a peripheral pulmonary mass and no roentgenographic evidence of mediastinal widening.