Background: Vitamin D has a significant role in the metabolism of calcium and bone. Therefore, its deficiency leads to rickets in growing children and osteomalacia in adults. The classical functions of Vitamin D in bone metabolism and calciumphosphorus homeostasis is well established. The non-classical functions of Vit D as an immunomodulatory and growth-promoting factor influencing the overall well being in general and respiratory health, in particular, is the subject of current interest. It is reported that vitamin D plays a crucial role in foetal lungs proper growth and maturity.In many children with steroid-resistant asthma, vitamin D supplements may increase the responsiveness to steroids. Vitamin D deficiency states were reported to be associated with an increased risk of acute exacerbations of bronchial Asthma. Our study is conducted to determine serum levels of vitamin D in asthmatic children and association of vit D deficiency with asthma. Aim of The Study:To determine the serum levels of vitamin D in asthmatic children. Objective: To Study the relation between vitamin D levels and 1. The severity of asthma 2. Frequency of asthma exacerbation Study Design:It is cross sectional study. Methods: 100 children who got admitted to the pediatric ward (or) PICU of MIMS, of whom 40 were known asthmatics and 60 age and sex-matched controls were considered to do a comparative study of the variables under consideration. Study of vitamin D levels in relation to bronchial asthma in children has been carried out as an analytical case-control study for 18 months. Results: 60% of the study participants were vitamin D deficient. Whereas 15% had insufficient levels, and sufficient vitamin D levels are observed only in 25% of the participants. A statistically significant difference in vitamin D levels and the severity of illness has been observed among the study participants. Moderate persistent Asthma has been seen more in patients who are deficient in vitamin D. A high statistically significant association has been observed between exacerbations of Asthma and levels of vitamin D. Conclusion: A statistically significant difference in vitamin D levels and the severity of illness among the study participants are observed. Moderate persistent Asthma has been seen more in patients who are deficient in vitamin D. A high statistically significant association has been observed between exacerbations of Asthma and levels of vitamin D.