Vitamin D is known to play an important role in bone metabolism through regulation of calcium and phosphate homeostasis and may also play an important role in immune system regulation. Vitamin D is produced by the body during exposure to sunlight, but is also found in oily fish, eggs and fortified food products. Infants are born with low vitamin D stores and are dependent on breast milk, sunlight or supplements as sources of vitamin D in the first few months of life. As the vitamin D content of breast milk is dependent on maternal vitamin D status and is often low, and sun exposure may be restricted for infants living at higher latitudes or for cultural or other reasons, infants are particularly vulnerable to vitamin D deficiency. Vitamin D deficiency in infants can lead to bone malformation (rickets), seizures and difficulty breathing. Current evidence suggests that vitamin D supplements may be effective in preventing rickets, particularly for infants and children who may be at higher risk due to limited sun exposure or those with darker skin pigmentation, however further research is needed before specific recommendations can be made. Hence the present study was planned for Observation of Vitamin D Deficiency in Newborn and Its Overcome by Oral Vitamin D Supplements. The present study was planned in Department of Pediatrics, Government Medical College, Bettiah, West Champaran, Bihar. The 50 cases of the term new borns were delivered to our hospital were enrolled in the present study. The cord blood was collected in plane tube, serum separated and tested for serum vitamin D, calcium phosphorus and ALP by immune assay technique. The values are noted. Then the babies with the vitamin D deficiency/insufficiency were supplemented with single high dose of vitamin D 60000 IU orally. And followed up after 45 days with estimation of serum vitamin D, calcium phosphorus and ALP. The data generated from the present study concludes that Most of our new borns, are born with vitamin D deficiency or insufficiency, and only a few babies have adequate serum vitamin D levels at birth. A single high dose of Oral vitamin D 60,000 IU is sufficient to normalise serum vitamin D levels with none developing hypervitaminosis.