The ideas of the biological role of vitamin D have been recently expanded substantially; the latter is considered as D hormone with immunomodulatory and anti-inflammatory properties, which can be used in the etiopathogenetic treatment of endometriosis. The paper provides an analytical review of the publications by Russian and foreign authors assessing the present ideas about the role of vitamin D in metabolic processes and about the possible relationship of vitamin D to the development of endometriosis. The publications show that the risk of endometriosis may be related to dietary vitamin D intake and plasma hydroxyvitamin D concentrations. The receptors of vitamin D and its metabolic enzymes (24-hydroxylase and 1α-hydroxylase) were found in the normal cyclic endometrium, as well as in the eutopic and ectopic endometrium of patients with endometriosis. The metabolite of vitamin D3 (cholecalciferol) calcitriol [1,25 (OH)2D] affects the endometrium by regulating gene transcription and immunomodulatory effects. There is dysregulation of a number of enzymes and vitamin D receptors (VDR) in the endometrium of patients with endometriosis. The expression of the NOHA10 gene has been found to be impaired in endometriosis-associated infertility. Vitamin D therapy can decrease the frequency and severity of pain in endometriosis. VDR agonists can reduce the risk of endometriotic lesions and the rate of disease recurrences. Analysis of the relationship between vitamin D and endometriosis can expand our understanding of the etiology and pathogenesis of the disease and perform its rational prevention and therapy. The pathogenetically grounded prevention and treatment of endometriosis is the use of cholecalciferol (Detrimax) for identified vitamin D deficiency,