Background: Transudative effusions are the ultrafiltrates of plasma that have been forced out of the pleura by an imbalance between the oncotic and hydrostatic forces in the chest which creates an imbalance. Also, exudative effusions occurs resulting from various inflammatory conditions. Methods: A total of 100 patients were enrolled to conduct a study comparing the diagnostic usefulness of pleural fluid bilirubin/serum bilirubin ratio to pleural fluid protein/serum protein ratio to distinguish between exudative and transudative pleural effusion. Results: Based on pleural fluid bilirubin to serum bilirubin ratio, 45% of the effusions were exudates and 55% were transudates. There were a total of 47% transudates and 53% exudates based on the criterion of pleural fluid protein to serum protein ratio. Significant correlation was seen between effusion type based on pleural fluid protein to serum protein and pleural fluid bilirubin and serum bilirubin. Conclusion: As a diagnostic tool, the pleural fluid bilirubin/serum bilirubin ratio exhibits potential in distinguishing between transudativeandexudativepleuraleffusions.