Introduction: Vitamin D deficiency in children is associated with short stature, underdevelopment, respiratory infections, and many other features that increase the risk of childhood complications. Various studies have been conducted on different and appropriate strategies for the treatment of vitamin D deficiency that there are disagreements about the use of vitamin D3 or vitamin D2, oral versus intramuscular (IM), fixed or titrated doses, low daily doses or intermittent high doses. (17) This study also attempts to answer one of these cases and designed to compare the effect of vitamin D injectable form versus oral pearl vitamin D on serum vitamin D level in children with vitamin D deficiency referred to Taleghani Gorgan Training Center. Material and Methods: In this study, one group was given 1 pearl vitamin D every week for eight weeks, and the second group was given a single dose of vitamin D 300,000 unit after 1 month and 3 months of treatment. Serum vitamin D levels were measured in all patients at Taleghani Gorgan Medical Center by one person and with one kit at all stages (baseline, 1 month, and 3 months after treatment). Results: In this study, 118 patients were enrolled in the study, 5 in the oral treatment group and 4 in the injection treatment group were excluded due to lack of follow-up, discontinuation of medication and incomplete patient records. Finally, 54 patients were in the oral treatment group and 55 in the injection treatment group. The mean age of the patients was 8.21 years. The frequency distribution of patients in both groups was evaluated by gender. In the oral treatment group, 22 (40.7%) were male, and 15 (27.3%) were male. Which was not statistically significant (p = 0.138)the changes in vitamin D 4 weeks after treatment and 3 months after treatment did not differ by gender and body mass index. (p >0.05).Changes in vitamin D levels 4 weeks after treatment and 3 months after treatment in the oral and injection groups were evaluated by age (less than 8 years old / over 8 years old), which was statistically significant in the oral treatment group. (p >0.05).But in the injection treatment group, the increase in vitamin D after 4 weeks was significantly greater in the age of 8 and less compared to the age of greater than 8 years (27.60 vs. 20.85 and p = 0.048,). In Longterm, 3 months later, there was no difference. (p>0.05) Conclusion: The results of the present study and previous studies show that both oral and injectable vitamin D therapy is equally effective in treating this deficiency in children. However, our study has shown that in younger children, injectable form in the short term yields a better response, but further studies with larger sample sizes are needed to generalize these results.