Abstract : Vitamin D, traditionally associated with the regulation of calcium–phosphate homeostasis, also plays a key role in women’s reproductive health. The presence of the vitamin D receptor (VDR) and its metabolic enzymes in the ovaries, endometrium, and placenta indicates its direct involvement in folliculogenesis, steroidogenesis, embryo implantation, and the maintenance of pregnancy. Evidence suggests that vitamin D deficiency may be linked to ovulatory disorders, menstrual irregularities, and reduced oocyte quality, as well as to the pathogenesis of polycystic ovary syndrome (PCOS), endometriosis, and infertility. Although vitamin D supplementation shows potential in improving metabolic and reproductive parameters, clinical findings remain inconsistent, particularly regarding the effectiveness of assisted reproductive technologies. During pregnancy, adequate vitamin D status is associated with a lower risk of preeclampsia, gestational diabetes, and with beneficial effects on fetal skeletal and immune development. Given the high prevalence of deficiency and the variability in individual responses to supplementation, further high‑quality studies are needed to precisely determine its clinical significance in women’s reproductive health.