Etiological factors of bone metabolism disorders in inflammatory bowel diseases have been the subject of interest of many researchers. One of the questions often raised is vitamin D deficiency. Calcitriol acts on cells, tissues and organs through a vitamin D receptor. The result of this action is the multi-directional effect of vitamin D. The reasons for vitamin D deficiency are: decreased exposure to sunlight, inadequate diet, inflammatory lesions of the intestinal mucosa and post-gastrointestinal resection states. This leads not only to osteomalacia but also to osteoporosis. Of significance may be the effect of vitamin D on the course of the disease itself, through modulation of the inflammatory mechanisms. It is also necessary to pay attention to the role of vitamin D in skeletal pathology in patients with inflammatory bowel diseases and thus take measures aimed at preventing and treating these disorders through the supplementation of vitamin D.