Cystic fibrosis (CF) currently affects around 30,000 individuals in the United States. Mucus obstructing the pancreas affects the production of digestive pancreatic enzymes causing pancreatic insufficiency, which leads to malabsorption, specifically of fat-soluble vitamins. New complications such as CF-related bone disease have also increased. Poor bone health is associated with malnutrition, inflammation, and vitamin D deficiency. CF patients generally have inadequate levels of 25-hydroxyvitamin D. Insufficient vitamin D status is linked with decreased bone mass, increased inflammation, decreased immunity, and is also believed to contribute to respiratory failure. The purpose of this research is to examine the associations between serum vitamin D, bone mineral density (BMD) and lung function within the pediatric CF population. It is hypothesized that there will be a positive association between serum vitamin D and bone mineral density. It is further hypothesized there will be a positive association between serum vitamin D and lung function. A retrospective chart review was conducted to evaluate the association of serum vitamin D by assessing pre and post serum vitamin D concentrations, BMD, and pulmonary function in 30 CF pediatric patients ages 8-18. Data was subjected to descriptive statistics, correlational analyses, and multiple linear regression to examine potential relationships between serum vitamin D levels with forced expiratory volume (FEV1) at baseline and with both BMD and FEV1 after 2 years of maximum dose supplementation. Independent t tests were ran to compare differences in groups regarding supplementation doses. No significant associations were found in serum vitamin D and BMD except in the baseline model. Furthermore, no significant associations were found between serum vitamin D and FEV1 values of lung function. Significant associations were seen in BMD and lean body mass at baseline and 2 years. Results also showed no significant differences between groups receiving either 2000 IU or 3000 IU vitamin D supplementation. While there were no consistent associations with serum vitamin D and BMD, baseline associations show a link between low serum levels and BMD. Future research should focus on interventions for preventative care of maintaining adequate vitamin D serum levels and diets rich in calcium for optimal bone health.