Tuberculosis (TB) is caused by infection with . Sometimes it is difficult to distinguish between active and inactive pulmonary TB based on chest X-ray images. TB biomarkers are needed to diagnose active TB when TB bacilli are not detected either through microscopic examination, culture or geneXpert MTB/Rif. Neopterin can be used as an additional diagnosis and therapy monitoring as well as assessing activation of macrophage cells. This study aims to examine and comparing serum neopterin levels in new cases of pulmonary TB with positive AFB and inactive pulmonary TB.This was an analytic study with Cross-Sectional design conducted in Dr. Soetomo General Hospital Surabaya, Indonesia. The subjects of the study were the new cases of pulmonary TB with positive AFB and inactive pulmonary TB who met the inclusion and exclusion criteria. Blood serum was collected and examined to measure neopterin serum levels in patients by ELISA technique.There was a significant difference of mean neopterin serum levels between the new cases of pulmonary TB with positive AFB and inactive pulmonary TB with a p-value <0.001 (74.92 nmol/l vs. 9.84 nmol/l). There was a significant difference in serum neopterin levels in each AFB grading in the new cases of pulmonary TB with positive AFB with a p-value <0.001 (60.10 nmol/l in AFB 1+, 80.81 nmol/l in AFB 2+, and 110.70 nmol/l in AFB 3+).Serum neopterin levels in the new cases of pulmonary TB with positive AFB were higher than inactive pulmonary TB.