Vitamin D deficiency has received increased academic interest because of its association with many common disease processes. The goal of our study was to document the prevalence of vitamin D deficiency. A retrospective chart review of 25-hydroxyvitamin D (ng/ml) levels at the University of Tennessee Health Science Center was conducted on general internal medicine patients over an 18-month period. The 25-hydroxyvitamin D deficient patients were divided into four groups: severe (<7 ng/ml), moderate (7.0-20.9 ng/ml), mild (21-31.9 ng/ml), and sufficient (>32 ng/ml). We found that an overwhelming majority of our patients were mildly to severely deficient (87 percent) with 17 percent severely deficient, 53 percent moderately deficient, 17 percent mildly deficient, and only 13 percent sufficient. The prevalence of 25-hydroxyvitamin D deficiency among this population was higher than expected based on the prevalence of 25-hydroxyvitamin D deficiency reported in literature. Based on this data, we believe a greater percentage of the general population needs to be studied in order to discover the true prevalence of vitamin D deficiency.