Giant cell carcinoma of the lung is an unusual form of pulmonary malignancy that follows an extremely aggressive clinical course. We report the clinical and roentgenographic manifestations of 14 patients with pathologically proven giant cell carcinoma of the lung, and compare our data to other reports in the literature. Our patients often presented with or developed constitutional or nonthoracic symptoms. This neoplasm was characterized by early evidence of widespread metastases. However, extension of tumor to the chest wall was not as frequent in our series as has been previously described. The survival from the time of diagnosis was extremely short. Any hope of successful treatment of this neoplasm depends on prompt, early diagnosis. Pulmonary giant cell carcinoma should be included in the differential diagnosis of large, round or oval, sharply outlined peripheral lung masses.