Vitamin D plays a central role in calcium and phosphate homeostasis, and it is essential for the proper development and maintenance of bone. Recent studies show that vitamin D is effective for different tissue functions in addition to bone metabolism. The study group was comprised of 101 healthy newborn infants with a gestational age of 38 weeks or more. Umbilical cord 25(OH) D levels were measured. Newborns were divided into two groups according to the 25(OH) D levels (<12 ng/ml and >12 ng/ml). Thirty-one percent of these newborn infants had severe deficiency. There were no differences between the groups according to the mother’s education, clothing style, home condition, profession, gestational age, vitamin D supplementation, newborn’s gender, and birth weight. Anahtar Kelimeler : vitamin D, kord kanı, yenidoğan.