Objective: The aim was to determine adenosine deaminase (ADA) and alkaline phosphatase (ALP) activity in sputum for the diagnosis of pulmonary tuberculosis.Methods: This study comprised of 64 subjects (33 pulmonary tuberculosis and 31 lung cancer). The ADA and ALP activity was measured in sputum and serum.Results: The mean ADA activity in sputum, serum and mean sputum/serum ADA ratio was 205.20 IU/L, 42.32 IU/L and 4.90 in pulmonary tuberculosis and 127.74 IU/L, 29.90 IU/L and 4.27 in lung cancer subjects respectively. The mean ALP activity in sputum, serum and mean sputum/serum ALP ratio was 461.34 IU/L, 159.24 IU/L and 2.90 in pulmonary tuberculosis and 226.64 IU/L, 119.87 IU/L and 1.99 in lung cancer subjects respectively.Conclusion: The mean ADA and ALP activity was significantly increased in pulmonary tuberculosis as compared to lung cancer subjects and hence may be a useful tool for the diagnosis of pulmonary tuberculosis.