Pulmonary tuberculosis is the most common infection among mycobacterial diseases in humans. Mycobacterium tuberculosis (MTB) is the causative agent for this disease. Pakistan is ranked 5th among high burden countries for tuberculosis. The goal of study was to measure the quantity of INH in the fixed dosage form prescribed to the patients and secondly to determine the serum levels of INH in pulmonary TB patients. Mortality rate was zero during the study. There was gain of body weight, improved serum hemoglobin levels, fever & cough settled during treatment period. This reflects the clinical improvement of patients by anti-tuberculous drugs. Therapeutic drug monitoring (TDM) for anti-tuberculous drugs is not a routine in our setup. In the light of increasing multidrug resistant & extensively drug resistant tuberculosis cases, the use of TDM should be reviewed in current evaluation of severely ill TB patients.