The clinical presentation, clinical course, and results of various treatment modalities of 17 patients with carcinosarcoma of the lung were reviewed. This group of patients was 0.2% of all Mayo Clinic patients with lung cancer who had been treated between 1971 and 1982. Most patients were men in the sixth decade of life who had a history of smoking. Ten of 17 neoplasms were located in the upper lobes. Noninvasive diagnostic tests had a low yield in detecting carcinosarcomas. Pulmonary resection with curative intent was performed in 15 of 17 patients; however, only 4 patients were alive at 6, 8, 28, and 39 months, respectively, postoperatively. The median survival was 1 year. Doxorubicin-based chemotherapeutic programs produced an objective response in two of four patients.