Background: Evaluation of adenosine deaminase (ADA) has emerged as a potential biochemical marker for the diagnosis of tuberculosis (TB). An increased level of ADA in blood generally indicates the presence of TB. This study aimed to evaluate the ADA level in pleural fluid with diagnostic accuracy in histologically confirmed patients of pleural TB. Materials and Methods: This prospective observational study included patients with a confirmed diagnosis of pleural effusion. Data related to demographics, clinical characteristics, sputum status, predominant cells, ADA levels, and pleural biopsy reports were recorded. Results: Of the 82 patients of exudative pleural effusion, 65 (79.3%) were men. The most common presenting symptoms were cough (87.8%), chest pain (67.1%), fever (64.6%), and shortness of breath (56.1%). The average ADA level was 66.5 IU/L. Pleural biopsy showed that 45.1% of patients were tubercular etiology, 34.1% of patients were malignant, and 20.7% were of nonspecific inflammatory origin. Totally 59.8% of patients had right-sided pleural effusion, whereas 40.2% of patients had left-sided pleural effusion. Majority of the TB patients (81.1%) with ADA level > 40 U/L were diagnosed with tubercular granuloma, whereas 41 patients with malignancy and other patients had ADA level < 40 U/L (P < 0.001). Conclusion: Evaluation of ADA level along with histopathological examination can be easily performed as the routine test in the diagnosis of TB.