Objective: The object of this study is to evaluate the relation between 25- hydroxy cholecalciferol (vitamin D₃) deficiency and allergic rhinitis by detecting level of 25-hydroxy cholecalciferol and Immunoglobulin E serum levels.
 Methods: This is a case-control study in which we compare two groups; group A included 69 patients diagnosed as allergic rhinitis (AR) and group B included 60 healthy individuals. Serum levels of cholecalciferol and serum levels of immunoglobulin (IgE) were assessed in all participants of both groups of this study.
Results: Serum level of 25- hydroxy cholecalciferol in group A (AR patients) was statistically significantly lower (mean ± SD: 14.2±8.04 ng/ml) than serum level of 25-hydroxy cholecalciferol in group B (21.1±8.2ng/ml). Also serum level of IGE in group A was markedly elevated in comparison to group B (494.4±61.7u/l) vs. (189.9±52.9u/l) with highly statistically significant difference (p-value < 0.001).
Conclusion: There is statistically significant relation between 25-hydroxy cholecalciferol  deficiency and allergic rhinitis; further studies must be done to assess the effect of Vitamin D₃ therapy in allergic rhinitis.