A total of 101 patients aged 18 to 55 years old with a tibia or femoral shaft fracture receiving intramedullary nailing for fracture fixation were randomized to receive vitamin D3 supplementation of 150,000 IU at injury and 6 weeks, 4000 IU/day for 3 months, 600 IU/day for 3 months, or the placebo. The primary outcomes of interest were radiographic healing scores (Radiographic Union Scale in Tibial Fractures) and clinical healing scores (Function Index for Trauma), measured at 3 months post-treatment. Results demonstrated that no statistically significant differences were observed between the 4 groups for radiographic and clinical outcomes measured at 3-months follow-up (p>0.50). Furthermore, no statistical significant differences were observed between all high dose groups vs low dose groups (p>0.4), low dose vs placebo groups (p>0.51), high loading dose vs high daily dose groups (p>0.62). The subgroup of vitamin D deficient patients revealed no statistically significant differences between the 4 groups was observed in both radiologic and clinical healing scores (p>0.4).