Differential diagnosis of distinguishing between extrahepatic and intrahepatic biliary obstruction is veryimportant because of surgical correction within the first 4 weeks of life is mandatory in isolated atresia of theextrahepatic bile ducts if irreversible changes in the parenchyme are to be avoided. The conventional liverfunction tests are little use in this respect and punch biopsy of liver is not without harzard. The radioactiveRose Bengal scanning and detection of fecal excretion are best method for differential daignosis of infantilejaundice. In Yonsei University, We report 7 cases of infantile Jaundice which were diagnosed by I-131 Rose Bengalliver and abdominal scanning with confirming by operation or liver biopsy. Case 1 ; Non-excretion of I-131 RoseBengal into the interstinal tract until 72 hours after IV injection and was diagnosed for Congenital BiliaryAtresia by opeartion. Case 2; Small excretion of I-131 Rose Benal into the intestinal tract until 48 hours afterIV injection and was diagnosed for Choledochal Cyst by operation. Case 3; Non-excretion of I-131 Rose Bengal intothe intestinal tract until 48 hours after IV injection and was diagnosed for Congenital Biliary Atresia byoperation. Case 4: Non-excretion of I-131 Rose Bengal into the interstinal tract until 72 hours after IV injectionand was diagnosed for Neonatal Hepatitis with Bile Stasis by liver biopsy. Case 5: Non-excretion of I-131 RoseBengal into the intestinal tract luntil 48 hours after IV injection and was impressed for complete obstruction ofbiliary tree on I-131 Rose Bengal scanning. Case 6: Small excretion of I-131 Rose Bengal into the intestinal tracton 48 hours abdominal scanning and was impressed for partial obstruction of biliary tree on I-131 Rose Bengalscanning. Case &; Small excretion of I-131 Rose Bengal into the intestinal tract on 48 hours abdominal scanningand was impressed for partial obstruction of biliary tree on I-131 Rose Bengal scanning.