The aim of the current study was to determine the possible crucial role of cancer antigen 125 (CA125) in the diagnosis of pulmonary tuberculosis (PTB). The CA125 levels of study and control groups were statistically compared. In a total of 146 patients that were included in the current study, 30 had active PTB, 37 inactive PTB, 28 community-acquired pneumonia (CAP), 25 pleural or pulmonary malignancies, and 13 patients exacerbation of chronic obstructive pulmonary disease. The mean CA125 levels in PTB, inactive PTB, CAP, and pleural-pulmonary malignancies were 118.46 +/- 248.41, 40.80 +/- 50.95, 47.76 +/- 60.76, and 57.77 +/- 65.59, respectively. For active-inactive discrimination of PTB, with a cut-off level of >35 U/ml, the sensitivity, specificity, positive predictive value, and negative predictive value of CA125 were 63, 59, 56, and 67%, respectively. Increased CA125 levels were detected in active PTB in the current results. The current results also show that high level CA125 should be reconsidered in the prediagnosis and/or discrimination of active and inactive PTB patients.