From June 1983 to September 1984, the pleural biopsies with Cope needle were performed at department of thoracic and cardiovascular surgery, Pusan Paik Hospital, Inje college, on 78 patients for exudative pleural effusion caused by various conditions. These results were analyzed clinically and summarized as follows: 2. The accuracy of pleural biopsy was 69.2% [54 of 78 patients]. The accuracy represented by ratio for the number of biopsy was 63.5% [54 of 85 biopsies]. 3. Among 61 patients of tuberculosis or malignancy, 37 [60.7%] were confirmed by pleural biopsy. 4. Tuberculosis was diagnosed in 48 patients, in 26[54.2%] out of these by pleural biopsy alone, in 3[6.2%] by pleural biopsy and isolation of AFB, in 2[4.2%] by pleural biopsy and operation, in 4[8.3%] by isolation of AFB, in 2[4.2%] by operation, and in 11[22.9%] clinically. 5. Among 13 patients of malignancy, 4[30.8%] were diagnosed by cytology alone, 4[30.8%] by pleural biopsy and cytology alone, 4[30.8%] by pleural biopsy and cytology, 1[7.7%] by pleural biopsy alone, 1[7.7%] by pleural biopsy and operation, and remained 3 by operation, lymph node biopsy, or bronchoscopy respectively. 6. False positive of clinical diagnosis was 12.5% for tuberculosis and 28.6% for malignancy. In pathological diagnosis there was no false positive. So specificity of pleural biopsy was very high. But false negative of pleural biopsy was 29.2% for tuberculosis and 46.2% for malignancy. 7. 4 cases[5.1%] of minimal pneumothorax were in the early series.