BACKGROUND: The percutaneous pleural needle biopsy have been regarded as cornerstone in the diagnosis of lymphocyte dominant pleural effusions of which acid fast bacilli smear and cytologic exam was negative. However, the complications of percutaneous pleural needle biopsy is not rare arid its diagnostic efficacy is not always satisfactory. Recently, pleural fluid adenosine deaminase (ADA) and carcinoembryonic antigen (CEA) are widely accepted as markers of tuberculous pleurisy arid malignant pleural effusion respectively. We designed this study to re-evaluate the role of percutaneous pleural needle biopsy in the diagnosis of lymphocyte dominant exudative pleural effusions whose APE smear, cytologic exam was negative. METHODS: Retrospective analysis of 73 cases of percutaneous pleural needle biopsy in case of lymphocyte dominant exudative pleural effusions whose AFB smear and cytoloic exam was negative from Jan 1994 to Feb 1996 was done. RESULT: In 35 cases, specific diagnosis was obtained(all cases were tuberculous pleurisy), arid in 3(1 cases specific diagnosis was not obtained in spite of getting adequate pleural tissues, and in the other 8 cases, percutaneous pleural biopsy failed to get pleural tissues. In 9 cases, complications were combined including pneuomothorax and hemothorax. All 49 cases of pleural effusions whose ADA value was higher than 40IU/L and satisfying other categories were finally diagnosed as tuberculous pleurisy, however, the pleural biopsy confirmed only 28 cases as tuberculous pleurisy. In 6 cases of pleural effusions of which CEA value is higher than l0ng/ml, the pleural biopsy made specific diagnosis n no case. Final diagnosis of above 6 cases consisted of 4 malignant of fusions, I malignancy associated effusion and I tuberculous pleurisy. CONCLUSION: In the diagnosis of 73 cases of lymphocyte dominant pleural effusions of which acid fast bacilli smear and cytologic exam was negative, percutaneous pleural biopsy diagnosed only in 35 cases. In the diagnosis of tuberculous pleurisy, the positive predictive value of higher ADA than 40 IU/L in lymphocyte dominant pleural effusion with negative AFB smear and negative cytologic exam was l00%. And the diagnostic efficacy of pleural biopsy was 57%. In cases of effusions with high CEA than 10ng/ml 83% and 0% respectively. Finally, we concluded that percutaneous pleural needle biopsy in the diagnosis of APE smear negative and cytologic exam negative lymphocyte dominant exudative pleural effusion was not obligatory especially in effusions with high ADA and low CEA value.