Enzyme-linked colorimetric analysis and radioimmunoassay were employed to detect serum fasting total bile acids (FBA) and choloyglycin (CG) respectively in cases of 32 neonatal hepatitis, 33 cases of neonatal unconjugated hyperbilirubinemia and 34 cases of breast milk jaundice (BMJ). FBA and CG in acute period of neonatal hepatitis were obviously elevated and decreased gradually in convalescent and recovered period. The difference was significant for each stage as compared with controls. Acute FBA correlated strongly with the course. Both neonatal unconjugated hyperbilirubinemia and BMJ differed significantly from controls in FBA and CG. The results suggested that serum FBA and CG were helpful in judging the course and state of neonatal hepatitis, and cholestasis might existed in neonatal unconjugated hyperbilirubinemia.