Aim: Neonatal bilirubin-induced neurologic dysfunction can present with a wide spectrum of symptoms from mild neurologic impairmentto severe acute bilirubin encephalopathy. In this study, we aimed to determine the risk factors of unconjugated hyperbilirubinemia amonghospitalized infants with serum total bilirubin levels ≥25 mg/dL and evaluate the effects of high serum bilirubin levels due to hemolysis onneurodevelopmental outcome at postnatal between 18 and 24 months.Materials and Methods: Thirty-six term infants were enrolled in the study. The patients were divided into two groups according to their conditionof either hemolytic or nonhemolytic hyperbilirubinemia. Neurodevelopmental assessment with The Bayley scale of Infant Development-II atpostnatal between 18 and 24 months was performed on all infants.Results: Fourteen infants (38.9%) were in the nonhemolytic group, while 22 (61.1%) were in the hemolytic group and there was no statisticallysignificant difference between the groups in terms of the measured mean Mental Developmental index and Psychomotor Developmental indexscores. All 4 patients who underwent exchange transfusion had subgroup incompatibility and their Psychomotor Developmental index scoreswere significantly lower (p<0.05).Conclusion: In our study, we found that subgroup incompatibility was an important risk factor for hemolytic indirect hyperbilirubinemia andthat the mean psychomotor neurodevelopmental score associated with high hyperbilirubinemia may be lower in these patients. We believethat larger case series studies are needed to discuss the relationship between subgroup nonconformity and neurodevelopmental outcomes.