Objective:Relevance of estimation of pleural adenosine deaminase(PADA) and serum adenosine deaminase (SADA) levels in-pleural effusion especially in cases of lymphocytic predominant exudative tubercular effusions. Methods:Fifty patients(33 male and 17 female;age:44.12±11.51 years) with pleural effusions were selected to assay adenosine deaminase(ADA) activity in pleural fluid and serum in adjunct to pleural fluid analysis.Effusions were individually classified as transudates or exudates after careful evaluation of all the biochemical parameters of pleural fluid and serum of patients and on the basis of Lights criteria.Cutoff value for PADA was taken as 60U/L and that for pleural/serum ADA ratio(P/S ADA) was 1.8.Results:Fourty -three patients had exudative effusions among which 38 patients had tuberculous pleural effusions and 5 had nontubercular effusions.7 cases were transudates.Mean PADA levels in tubercular group(78.95±25.32 U/ L) were found to be much higher P=0.0000) than nontubercular(23.00±5.22 U/L) group.SADA levels in tubercular group(31.05±6.42 U/L) were significantly higher(P=0.0000)as compared to nontubercular group(15.58±8.35 U/L).PADA cutoff at 60 U/L yielded sensitivity and.specificity of 81.5%and 100%respectively,whereas P/S ADA ratio at 1.8 gave sensitivity and specificity of 84.2% and 75%respectively. A positive correlation(r=0.507,P= 0.001 1)between PADA and SADA was found in tubercular group but no such correlation(r=0.302,P=0.3407)was observed in nontubercular group.Conclusion: The measurement of ADA in tubercular pleural effusions has not only relevance but also a high diagnostic utility when other clinical and laboratory tests are either negative or confusing. Objective: Relevance of estimation of pleural adenosine deaminase (PADA) and serum adenosine deaminase (SADA) levels in-pleural effusion especially in cases of lymphocytic predominant exudative tubercular effusions. Methods: Fifty patients (33 male and 17 female; age: 44.12 ± 11.51 years) with pleural effusions were selected to assay adenosine deaminase (ADA) activity in pleural fluid and serum in adjunct to pleural fluid analysis. Effusions were individually classified as transudates or exudates after careful evaluation of all the biochemical parameters of pleural fluid and serum of patients and on the basis of Lights criteria. Cutoff value for PADA was taken as 60U / L and that for pleural / serum ADA ratio (P / S ADA) was 1.8. Results: Fourty -three patients had exudative effusions among which 38 patients had tuberculous pleural effusions and 5 had nontubercular effusions.7 cases were transudates.Mean PADA levels in tubercular group (78.95 ± 25.32 U / L) were found to be much higher P = 0.0000) than nontub (23.00 ± 5.22 U / L) group.SADA levels in tubercular group (31.05 ± 6.42 U / L) were significantly higher (P = 0.0000) as compared to nontubercular group (15.58 ± 8.35 U / L) A positive correlation (r = 0.507, P = 0.001 1) was between 81.5% and 100% respectively. P / S ADA ratio at 1.8 was 75% PADA and SADA was found in tubercular group but no such correlation (r = 0.302, P = 0.3407) was observed in nontubercular group. Confc: The measurement of ADA in tubercular pleural effusions has not only relevance but also a high diagnostic utility when other clinical and laboratory tests are either negative or confusing.