Tuberculosis is an oldest and common infectious disease. Detected as far back as 10,000 BC it still remains a major public health problem world wide The use of biological markers in the diagnosis of tuberculous pleural effusion (TPE) is a breakthrough Adenosine deaminase(ADA) has been proposed to be a useful surrogate marker for TB in pleural, peritoneal and pericardial fluids. Although sensitive it is not a specific diagnostic tool, but combined with other tests the sensitivity can be increased. Materials&methods; 100 patients of suspected TPE were studied .Sensitivity and specificity of pleural fluid ADA alone and in combination with Mantoux test, pleural fluid cytology studied. Conclusion; pleural fluid ADA (>63U/L) alone was essentially diagnostic of TPE, between 40-63U/L it is highly suspicious of TPE along with >50% lymphocytes in pleural fluid confirms the diagnosis.

Keywords: Tubercular pleural effusion; ADA; Mantoux test; Pleural fluid cytology.