For allergic rhinitis (AR), subcutaneous immunotherapy (SCIT) is proved to be effective in improving symptoms and outcome. It increases IL-10 production which helps in inducing peripheral tolerance to allergens. The role of vitamin D supplementation as an adjuvant to SCIT in patients with allergic rhinitis should be investigated. Objective of this study was to assess role of Vitamin D supplementation with SCIT in inducing tolerance to pollen, increasing IL10 and improving symptoms in AR patients. 48 AR patients were included. Skin prick test was done then baseline and final nasal symptoms scores rating, serum level of IL 10 and specific IgE were measured in two groups of patients; group 1 on SCIT and group 2 on SCIT and vitamin D supplementation. A statistically significant decrease of total nasal symptoms scores in group 2 when compared with group 1 (P < 0.001). IL 10 was increased in group 2 than group 1 with a statistically significant difference (P < 0.001) while, specific IgE was decreased in group 2 than group 1 with a statistically significant difference (P =0.01).There was a significant negative correlation between serum level of IL 10 and both nasal symptoms scoring and specific IgE (P < 0.001 and 0.028, respectively). In conclusion, serum level of IL 10 is significantly increased in AR patients on SCIT and Vitamin D supplementation.