Needle aspiration of a pulmonary mass may accurately delineate malignant from nonmalignant pulmonary lesions; however, needle aspiration may be unable to identify a specific cell type. Therefore, a retrospective review of patients undergoing needle aspiration of pulmonary masses was carried out for the years, 1979 through September 1984. A Lee needle was used, which produces a sample of tissue 1-mm in diameter suitable for histopathologic analysis as well as a cytologic specimen. A total of 87 needle biopsies were carried out, but only 46 patients later underwent resection. Five patients (6 percent) sustained a pneumothorax, and four required a chest tube. Minimal hemoptysis occurred in three patients (3 percent). Eight patients were subsequently found to have benign lesions, and there were 38 malignant tumors. Seven needle biopsies (18 percent; 7/38) were nondiagnostic and subsequently proved to be malignant. Thirty-one needle biopsies were diagnostic of malignant neoplasms (82 percent; 31/38). Twenty specimens showed the same cell type as the needle biopsy (65 percent 20/31). Eleven resected specimens disagreed with the cell type from the needle biopsy (35 percent; 11/31). In these 11 patients a change in management was indicated because of the delineation of a different cell type in only four (11 percent of all 38 patients with cancer). Mixed tumors and small cell carcinoma provide the area of most concern. Our conclusions are that needle biopsy accurately indicated a malignant neoplasm in 82 percent of the patients undergoing later resection and that the specimens from Lee needle biopsy accurately predicted the cell type in 65 percent of the specimens. The inaccurate histologic diagnosis was important clinically in only 11 percent of the patients. Overall, the needle biopsy of pulmonary lesions provided a correct decision on management in 87 percent of the cases in which biopsy provided diagnosis of a malignant neoplasm (31 patients).