BACKGROUND: Burn patients, due to their damaged skin, may not be able to synthesize vitamin D. In this study, we aimed to evaluate the effects of vitamin D supplementation on the recovery of hospitalized burn patients. METHODS: Fifty-four patients participated in a randomized controlled trial. Eighteen patients were randomly assigned to group C (control, received gelatin soft gel as placebo), 18 patients to group D RESULTS: There were no significant differences in the serum vitamin D levels between the groups at admission (P = 0.52), and 81.5% of the participants were deficient, with a noteworthy increase during study in supplemented groups (P <
0.001). The Bates-Jensen Wound Assessment Tool demonstrated significant differences in wound healing between the C group and the D CONCLUSION: Supplementation with vitamin D at doses of 1000 and 3000 IU/day improved wound healing and decreased scar thickness as well as exogenous insulin requirements. Overall, at 3000 IU/day, better results were achieved than at 1000 IU/day. TRIAL REGISTRATION: This article is registered in 24/04/2020 on the Iranian Randomized Clinical Trials Registry (trial registration number (IRCT, code: IRCT20200420047141N1.