Background: Tuberculosis (TB) is still a primary public health concern worldwide, the most common of which is pulmonary involvement. The official diagnosis of tuberculosis involves the culture of a tissue sample, which in turn takes time. Neopterin, as one of the indicators of cellular immune activity, is secreted by macrophages and T lymphocytes in different inflammatory phenomena due to the stimulation of interferon-gamma. Therefore, it may be possible to measure the serum level of Neopterin in the diagnosis and follow-up of the response to pulmonary and extra-pulmonary tuberculosis treatment. Objective: This study aimed to evaluate the serum level of Neopterin in the diagnosis of newly diagnosed pulmonary/extra-pulmonary tuberculosis. Method: Six groups of 20 individuals, including pulmonary TB, extra-pulmonary TB, healthy, proven rheumatologic diseases, patients with pulmonary malignancies, and finally, those with lung infections, entered the study. A serum sample was taken to assess the level of Neopterin. The samples were transferred to the laboratory in less than 30 minutes. Results: The level of Neopterin is significantly higher in patients with pulmonary TB into patients with extra-pulmonary TB, healthy and lung infections, and then in extra-pulmonary TB was significantly higher than in healthy individuals, patients with lung cancer and lung infection. Conclusion: According to the significant relation between serum Neopterin level in patients with pulmonary and extra-pulmonary TB compared to healthy people without any underlying disease, it may be possible to initiate specific pulmonary tuberculosis treatment in a shorter period. However, it is necessary to follow the tissue culture sample.