89 of 102 enrolled patients with long bone fracture were identified as vitamin D deficient and randomized to receive a single dose of oral 100,000 IU vitamin D within the initial 2 weeks post-injury or a placebo. The purpose of this trial was to investigate the rate of nonunion in this patient population and assess the feasibility of using acute high-dose vitamin D supplementation in patients with vitamin D deficiency. Nonunion rate was 2.3% in the treatment group (1 patient) and 6.7% in the placebo group (3 patients). One fixation failure was recorded in each group. Using the results from this study, full-scale, sufficiently-powered randomized controlled trials are needed to evaluate the efficacy and safety of high-dose vitamin D supplementation for nonunions in vitamin D deficient patients with long bone fracture.