The diagnosis of pleural tuberculosis (TB) continues to be a challenge in clinical practice. Traditional diagnostic methods are very useful for the diagnosis of pulmonary TB but have a low yield when applied to pleural fluid. It is produced during the inflammatory process triggered by the M. tuberculosis. Usefulness of adenosine deaminase (ADA) estimation in pleural fluid has been shown as a reliable chemical bio-marker specially when there is suspicion of tuberculosis in endemic areas. ADA level was determined in the pleural fluid of 100 patients present with pleural effusion admitted at Mymensingh Medical College Hospital during the period of March 2012 to September 2012. ADA level was >40IU/L among the 52 tubercular pleural effusion patients with sensitivity & specificity is 100% and 66% respectively. Thus is evident that ADA level can be used along with conventional methods for diagnosis of pleural TB.