We reviewed the laboratory parameters, clinical information including presence or absence of stool pigmentation, and ultrasonographic findings in 67 patients with neonatal conjugated hyperbilirubinemia and liver biopsies. Hepatobiliary nuclear scintigraphy was done in 14 of the patients. Final diagnoses included extrahepatic biliary atresia, neonatal hepatitis, cystic fibrosis, metabolic liver disease, alpha 1-antitrypsin deficiency, bile duct stenosis, Alagille syndrome (arteriohepatic dysplasia), choledochal cyst, panhypopituitarism, and miscellaneous causes of intrahepatic cholestasis. A single diagnostic criterion is insufficient to distinguish the various causes of neonatal jaundice. Clinical laboratory values varied widely among patients with medical and surgical causes of jaundice. Absence of stool pigmentation was not specific for biliary atresia and was found in patients with medical causes of jaundice. Conversely, two patients with biliary atresia had pigmented stools at presentation. Ultrasonography was diagnostic only for choledochal cyst and bile duct stenosis. Nonvisualization of the gallbladder by either ultrasonography or nuclear hepatobiliary scintigraphy was nonspecific in the discrimination of medical from surgical causes of jaundice. A multidisciplinary approach to the evaluation of neonatal jaundice is necessary, since no single test or imaging modality can reliably define the cause in all cases.