Radiologic-surgical correlative studies were performed for new pulmonary parenchymal nodules in 100 lungs of 84 patients with previously treated extrathoracic malignancies. Ten patients with radiographically typical bronchogenic carcinomas were excluded from analysis. Of 237 nodules resected, 173 (73%) were identified with computed tomography (CT) and 64 (27%) were not. Two hundred seven (87%) were of metastatic origin, 21 (9%) were benign, and nine (4%) were bronchogenic carcinomas. Of those nodules seen with CT and not with radiography of the chest, 84% were of metastatic origin. Between patients with carcinoma and those with sarcoma or melanoma, there was little difference in the percentage of nodules found with CT. More resected nodules were metastases in the sarcoma-melanoma group (93%) than in the carcinoma group (77%). New bronchogenic carcinomas and benign lesions were more common in the carcinoma group. Chest radiography disclosed all nodules resected in 44% of cases, whereas CT disclosed 78%. Of 65 nodules detected as solitary nodules with chest radiography, only 35 (54%) proved to be truly solitary, whereas 35 of 44 (80%) detected with CT were truly solitary.