Background: Low antioxidant system may contribute to the severity of neonatal hyperbilirubinemia. Aim of the work: This study was performed to clarify the relationship between serum   25-hydroxyvitamin-D (25[OH] D) and the hyperbilirubinemia in full-term neonates. Methods: This is a cross sectional case control study performed with the aim of determining whether there is an association between serum indirect bilirubin and serum vitamin D levels in newborns with jaundice at a level necessitating phototherapy. The study was carried on 60 full term newborns admitted to the Neonatal Intensive Care Unit of Minia University Hospital, from April 2017 to December 2017. They were classified into 2 groups, Group I: (cases): Newborns with postnatal ages of 3-10 days and gestational ages of 37-40 weeks, with a bilirubin level above the pre-set threshold for phototherapy as recommended by the American Academy of Pediatrics (AAP). Group II :( controls) 30 matched apparently normal healthy newborns were enrolled in the study as a control group. The study included the mothers of case group. All laboratory investigations were done in clinical pathology department, Minia University hospital. Results: Serum Vitamin D levels were significantly lower in patients than controls (p < 0.01). There was a strong negative correlation between neonatal total serum bilirubin level and neonatal serum vitamin D in cases group. In addition, we observed that there was a highly statistically significant positive correlation between serum vitamin D level of neonates and their maternal serum level was present. Conclusions: Indirect hyperbilirubinemia in full-term neonates is associated with decreased serum levels of (25[OH] D)