I reviewed the results of 143 Cope needle biopsies in 121 patients. Diagnostic biopsies were obtained in 26 patients. Two patients with rheumatoid pleuritis had suggestive pleural fluid. Seventeen of the 19 patients with malignancy had diagnostic pleural fluid cytology. Seven additional patients with nondiagnostic biopsies had diagnostic pleural fluid cytology. In four of five patients with tuberculosis, Mycobacterium tuberculosis grew from cultures of pleural fluid. One additional patient with a nondiagnostic biopsy also had a pleural fluid culture that grew M tuberculosis. Pleural biopsy was the sole means of diagnosis in only two patients. Diagnostic yield was not increased in the 21 patients who had multiple biopsies. In the diagnosis of malignancy, pleural fluid cytology was superior to pleural biopsy. In the diagnosis of tuberculosis, pleural fluid culture was as good as pleural biopsy. Cope needle biopsy should be done only when a strong suspicion of pleural malignancy or tuberculosis exists.