To differentiate biliary atresia from intraheaptic cholestasis, Tc-99m DISIDA hepatobiliary scintigraphies and percutaneous needle biopsies of 60 consecutive infants were evaluated retrospectively. Twenty three patients had biliary atresia and 37 patients intraheaptic cholestasis(neonatal hepatitis 34, TPN induced jaundice 2 and Dubin-Johnson syndrome i). All sixty patients underwent Tc-99m DISIDA hepatobiliary scintigraphy with phenobarbital pretreatment. Of 23 patients with biliary atresia, 22 were correctly interpreted showing 96% sensitivity while of 37 patients with intraheaptic cholestasis, only 12 had intestinal excretion of radionudide showing 32% specificity. Among the forty needle biopsies, 17 of biliary atresia and 23 of intrahepatic cholestasis, 37 were correctly interpreted as either having biliary atresia or intrahepatic cholestasis. The overall diagnostic accuracy was 93%. Of 3 misdiagnosed cases, the histologic findings of two patients with biliary atresia(aged 43 days and 54 days at the first needle biopsy) were essentially the same as those of neonatal hepatitis. Follow-up biopsies, however, showed findings consistent with biliary atresia. The third one(VLBW premie with history of 8 weeks of TPN) showed mild ductal proliferation and portal fibrosis. This was interpreted as suspicious for biliary atresia. Jaundice resolved gradually. In summary, patients who have intestinal excretion of radionudide on Tc-99m DISIDA hepatobiliary scintigraphy, biliary atresia can be ruled out. But the patients who do not have intestinal excretion of radionudide should have further investigation by needle biopsy. Judicious use of Tc-99m DISIDA hepatobiliary scintigraphy and percutaneous needle biopsy can give a diagnostic accuracy of 95% or more in cases of infantile cholestasis.