ABO iso-immunization is the most frequent hemolytic disease of the newborn. Treatment depends on the total serum bilirubin level, which may increase very rapidly in the first 48 h of life in cases of hemolytic disease of the newborn. Phototherapy and, in severe cases, exchange transfusion are used to prevent hyperbilirubinemia encephalopathy. Intravenous immunoglobulins are used to reduce exchange transfusion. Herein we present a female infant who was admitted to the our NICU because of ABO immune hemolytic disease and after two courses of 1gr/kg of IVIG infusion, she developed NEC. Administration of IVIG to newborns with significant hyperbilirubinemia due to ABO hemolytic disease should be cautiously employed and always administered under strict.