Introduction: A pleural effusion is accumulation of excessive fluid in the pleural space due to an imbalance between the production and absorption of pleural fluid by pleurae (visceral as well as parietal). Pleural effusion is a common clinical manifestation and about 3000 per Million people in the world suffers from pleural disease. Aims: To assess usefulness of ratio of serum LDH to Pleural Fluid ADA in differentiating Malignant Pleural Effusion and Tubercular Pleural Effusion. Materials and Methods: The study was a Descriptive Observational Cross-sectional study was conducted in Department of Respiratory Medicine, Kamala Nehru Chest Hospital, Dr S N Medical College Jodhpur (Rajasthan), and a tertiary care centre for Respiratory Disease in Rajasthan, India after getting clearance from the Ethical committee. Result: found that most patients with tubercular pleural effusion (n=20) had Pleural Fluid ADA levels >35 and majority of the patients had Biopsy proven Malignant pleural effusion [22 (44.0%)] and it was statistically significant (p< .00001), (z=4.1036). Conclusion: We found that, most number of patients had Tubercular Pleural Effusion. It was statistically significant and majority of the patients had Biopsy proven malignant pleural effusion and it was statistically significant.