ABSTRACT Background: Tuberculosis (TB) is a chronic disease caused by Mycobacterium tuberculosis, and the prevalence of tuberculosis in developing countries like Egypt still higher. Vitamin D is a fat-soluble vitamin that acting significant role against infectious diseases including tuberculosis, thus, human monocytes have receptors for vitamin D, which activates anti mycobacterial responses in human monocytes and macrophages through enhancing phagocytosis and granuloma creation. Objective: To assess the serum level of vit. D in patients newly diagnosed as pulmonary tuberculosis, at time of diagnosis and after sputum conversion to detect the effect of Vit. D on tuberculosis patients.  Subjects and Methods: The current study designed to evaluate the level of serum VD on group of patients with active pulmonary TB, as well as on healthy control subjects, in addition to measuring the level of VD after sputum conversion from positive to negative. The study conducted on Abbassia chest Hospital from the start of January 2020 until the end of December 2020, and included 50 patients with PTB and 20 healthy controls. Results: The level of TLC and PLT were significantly higher than in the control subjects, P < 0.001, while the HB level showed significant lower level, P < 0.001. The level of ESR was significantly higher in TB patients than in control groups, P < 0.001, it measured about (83.6± 30.7) mm/h, in TB group, opposite to (7.05± 3.03) mm/h, in control group. The level of VD in TB patients was significantly lower than in the control subjects; (30.3±10.2 versus 38.81± 3.48) ng/mL at the beginning of the study. The change of serum level of vitamin D was significant after sputum conversion, it elevated from 30.3±10.2 ng/L to 31.0.9±9.63 ng/L, P = 0.02. Conclusion: The present work concluded that; vitamin D deficiency was common in patients with pulmonary TB and that level was significantly associated with healing and good response to treatment.