The aim of this study was to evaluate the effect of vitamin D supplementation in women with hypovitaminosis D and “small burden” uterine fibroids.This study focused on 208 women diagnosed with uterine fibroids and concomitant hypovitaminosis D, from January to December 2014. One hundred eight women of the initial study population were diagnosed with “small burden” uterine fibroids. Among them, those who underwent a proper vitamin D supplementation constituted the “study group” (n = 53), while women who spontaneously refused the therapy or did not perform it properly, constituted the “control group” (n = 55). The characteristics of uterine fibroids, the fibroid-related symptoms, and the vitamin D serum levels were evaluated 12 months after the initial diagnosis.In women with uterine fibroids, a negative correlation emerged between the baseline 25-hydroxy-cholecalciferol (25-OH-D3) concentration and both the volume of the largest fibroid (r = −0.18, P = 0.01) and the total volume of fibroids (r = −0.19, P = 0.01). No correlation was found between the baseline 25-OH-D3 levels and the number of fibroids per patient (r = −0.10, P = 0.16). In women of the “study group,” a significant increase in the 25-OH-D3 serum level was observed after 12 months of supplementation, and a lower rate of surgical or medical treatment due to the “progression to extensive disease” was reported (13.2% vs 30.9%, P = 0.05).Supplementation therapy with 25-OH-D3 restores normal vitamin D serum levels in women with “small burden” fibroids. In these women, vitamin D supplementation seems to reduce the progression to an extensive disease, and thus the need of conventional surgical or medical therapy.