Background:TB has a long incubation period, with the timeline for transition from infection to expression lastingmonths or decades.Tuberculosis (TB) is a bacterial disease caused by the tubercle bacilli which includes Mycobacterium tuberculosis. TB remains one of the major health problems in Bangladesh andworldwide.

Objectives:Our study aim is to investigate the diagnostic value of serum ADA level (as an alternative method) for diagnosis of PTB.

Methods and Materials:3 ml of blood was taken from patients (40 nos) with Pulmonary Tuberculosis (PTB) and controls (40) under aseptic conditions and done the ADA assay in central laboratory of Biochemistry.ADA measured by Giusti and Galanticolometric method.

Result:Our results showed that mean serum ADA in pa­tients with pulmonary TB is significantly higher than in the normal population.

Conclusion:The present study shows that a simple,inexpensive, highly sensitive and specific test like ADA estimation should be employed routinely to differentiate between tubercular and non–tubercular etiology in patients.ADA may be used for early diagnosis of TB, especially in case of negative AFB smear from the body specimens.