Introduction: There are compelling suggestions from contemporary epidemiological studies that vitamin D deficiency has a role in infertility and multiple disease states. Vitamin D deficiency is associated with polycystic ovary syndrome (PCOS), endometriosis, uterine fibroids and premature ovarian failure. It influences the outcomes of in-vitro fertilization (IVF) and pregnancy. Aim: The aim of this study was to assess the prevalence of vitamin D deficiency and insufficiency among women with infertility compared to fertile women, at the Lagos University Teaching Hospital (LUTH). Study design: This was a comparative cross-sectional study.