Reparative giant cell granulomas are benign masses of multi-etiological nature, which account for 1%–7% of all benign lesions of the jaws. The objective of this case report is to present the relationship between isolated vitamin D deficiency and the development of reparative giant cell granuloma. Herein, we present the case of a 70-year-old female patient with a painless mass of increased mobility in the mandibular region, and pain in the involved teeth. After histological confirmation and laboratory screening, а reparative giant cell granuloma caused by serious deficiency of vitamin D3 - (25-OH)D was diagnosed. The treatment protocol included surgical removal of the lesion and vitamin D replacement therapy. In rare cases, this type of lesion can be a primary manifestation of vitamin D deficiency; therefore, it is extremely important to be aware of this pathology.