The records of 96 consecutive patients who underwent mediastinoscopy and were ultimately shown to have bronchogenic carcinoma were reviewed. Indirect tests for mediastinal tumor metastases in these patients included bronchoscopy and chest roentgenograms in all 96, mediastinal laminagrams in 65, esophagograms in 27, carinal biopsy in 23, bronchograms in 5, pulmonary angiograms in 5, azygograms in 2, and aortograms in 2 patients. Of the 43 patients in this series in whom all indirect tests revealed no metastases, mediastinoscopy showed nodal involvement in 11 (28%), who were thus spared unnecessary thoracotomy. On the other hand, if negative mediastinoscopy had not cast doubt on the validity of indirect tests that seemed to show metastases, an operation might actuallly have been denied to 14 patients who were ultimately proved to have anatomically resectable disease.