Vitamin D regulates calcium homeostasis in the body and may play a major role in regulating immune responses to tuberculosis (TB). Pilot studies suggest that vitamin D supplementation may improve outcomes in pulmonary TB (PTB), but clinical evidence using vitamin D in TB treatment is limited. We present a case of vitamin D deficiency in a woman with refractory drug-susceptible PTB. Antituberculous therapy and the correction of vitamin D deficiency resulted in clinical and microbiologic improvement at month 13 of her treatment. The basis for vitamin D/TB interactions and a brief literature review are discussed. Data from controlled trials are needed to evaluate the efficacy of vitamin D as adjunctive TB therapy.