From March 1986 to April 1987, 70 percutaneous needle aspiration (PCNA) procedures were performed in 66 consecutive patients. Seven immunocompromised patients had the procedure performed to obtain culture material from the lung, and 59 patients with chest lesions were analyzed. This includes 49 patients with either a lung nodule or mass. In the remaining ten patients, there were three chest wall or pleural lesions, two aortic pulmonary window lesions, two right hilar lesions, and three anterior mediastinal lesions. Forty of these 59 patients were ultimately proven to have a malignancy. The diagnostic yield for malignant disease by cytology and histology of PCNA was 97.5 percent (39 of 40). Twelve patients had a final diagnosis of benign disease. The diagnostic yield in benign diseases by PCNA was 91.6 percent (11 of 12). The remaining seven patients do not yet have a final diagnosis, though the clinical course favors benign disease in six of these patients. We attribute the major reason for this high specific diagnostic yield in both malignant and benign diseases to the ability of obtaining histologic specimens for interpretation.