A male infant presenting with neonatal hepatitis syndrome, characterized by conjugated hyperbilirubinemia and very mild liver function test abnormalities, at 2 weeks of age was found to have no excretion of radioisotope into the intestinal tract on hepatobiliary scan. Liver biopsy revealed severe interlobular bile duct paucity. Other features of Alagille's syndrome were not present; other conditions frequently associated with interlobular bile duct paucity were also excluded. Subsequently, the infant was found to have cystic fibrosis. Cystic fibrosis is thus another disease that may be associated with paucity of interlobular bile ducts presenting as neonatal hepatitis syndrome, and this represents a different pathogenesis of cholestatic jaundice in neonates with cystic fibrosis besides those previously recognized.