Introduction: Pleural effusion, that is commonly encountered clinical problem by the Pulmonologists and physicians.The gold standard for diagnosis of tuberculous pleuritis is detection of Mycobacterium tuberculosis bacilli in pleural fluid, either by microscopy/ molecular methods (CB-NAAT) and culture, or the histological demonstration of the caseating granulomas in biopsy specimen. Aims & objectives are to assess Significance of ADA level in the diagnosis of pleural effusion. Materials and method: The study was done in microbiology laboratory at Sir-T Hospital, Bhavnagar, Gujarat from January, 2020 to December, 2020 to Analysis of pleural fluid adenosine deaminase in diagnosis of tubercular pleural effusion. Adenosine Deaminase levels are evaluated by Adenosine Deaminase Assay Kit (DIAZYME). Observation & results: In our study, Total 48 pleural fluid samples were tested for ADA. Out of total 48 samples 34 were males and 14 were females in our study. However out of 48 samples, n20 samples positive for CB-NAAT. Out of the total 48 pleural fluid samples, 20 pleural fluid samples were positive (value >60 U/L) for ADA in our study. Conclusion: From this study, its concluded that Pleural Fluid Adenosine deaminase is important biomarker in diagnosing the Tubercular pleural effusion and can be useful aid in the day to day clinical practice.