**Abstract**

Neonatal indirect hyperbilirubinemia is one of the most frequent neonatal problems that affect almost two thirds of term infants. Although etiology of jaundice has been widely studied, identification of pathological causes presents constant clinical challenge. Our study group performed an extensive retrospective study of etiology of neonatal hyperbilirubinemia and showed high frequency (44.37%) of jaundice of undefined etiology. The group included exaggerated physiological jaundice, earlyand late-onset breast-milk jaundice, and no identifiable etiology. Other etiologies were neonatal infection, prematurity, birth trauma, and hemolysis represented with 15%. We described hematological parameters in both non-hemolytic and hemolytic type of jaundice; a significant correlation of relevant laboratory findings with etiology was established. In this chapter we will present our own data and perform a data-relevant literature review. Furthermore, investigation and management plan of neonatal indirect hyperbilirubinemia will be presented in accordance with own data and available literature.

**Keywords:** neonatal indirect hyperbilirubinemia, etiology, undefined jaundice, hemolysis, hematological parameters
