Neonatal jaundice alludes to the yellow hue of the skin and sclera of infants that outcomes from the testimony of bilirubin. VitB12 is critical for development and multiplication of red platelets (RBCs). Lack of The point of this examination was to assess variety in nutrient B12 level in embittered full term youngsters treated by phototherapy. Strategies: This examination was a case control study, which was done on 100 full term infants partitioned as cases gathering: fifty babies with jaundice treated by phototherapy, were tried out the investigation as an examination gathering. Control gathering: fifty ordinary full term youngsters. This investigation was led on infants who were conceded in the neonatal emergency unit Benha Children Hospital and Benha University Hospital) in the age gathering of 3-7 days. Full history, complete clinical assessment and research facility examinations included: serum VitB12 level before phototherapy and 24 hour after phototherapy were estimated. Results: Patient gathering was essentially connected with higher TSB when contrasted with control gathering, there were measurably huge lessening in Serum VitB12 level among cases bunch than control gathering. There was measurably critical negative connection between's serum VitB12 level and (complete serum bilirubin levels (TSB) and DSB. Serum VitB12 level was expanded after phototherapy. End: Full term children with backhanded hyperbilirubinemia had lower serum levels of nutrient B12 than sound full term youngsters. Phototherapy could build the degree of serum nutrient B12 in youngsters with roundabout hyperbilirubinemia.