Objective To evaluate clinical significance of pleural needle biopsy ( PNB) in diagnosis of pleural disease and its safety. Methods Totally, 594 cases with established pleural effusion, who were undergone PNB at least once in the First Hospital of Changzhou, Jiangsu province from June 1989 to September 2002, were studied retrospectively and analyzed. Results Sensitivity of PNB was 74% (302/ 408) for tuberculous pleurisy and 70. 2% (113/161) for malignant pleurisy. No characteristic pathological changes were found in PNB for the other 25 patients with pleural effusion due to other causes ( SLE, rheumatoid arthritis, leukemia, lymphoma, Castleman disease and Meigs syndrome) . Complications associated with PNB were pneumothorax (69. 0% ) , bleeding (31. 0% ) , fever ( 19. 0% ) and seeding of malignant cells (5. 0% ), and no special treatment was required for them, but one case of tension pneumothorax recovered uneventfully after 5 days of closed drainage. Conclusions PNB was a safe, simple and effective means of diagnosing tuberculous and malignant pleural effusion, and should be attempted extensively at grassroots hospitals. Seeding of malignant cells was uncommon, but should be kept in mind. Repetition of PNB could improve its sensitivity in diagnosis for malignant pleural effusion, with extremely few fatal complications.