Microcholangiography using microbarium was done for radiological observaton of the morphology of intrahepatic microbiliary system and its change after extrahepatic bile duct obstruction. Regurgitation of microbarium into the systemic circulation ws also observed. Extrahepatic bile ducts of 40 rabbits were ligated and microcholangiography was done just after ligation, after 1 day, 3 days and 5 days. Injection pressure of microbariu was 58cm Hsub 2O in 20 rabbits and 93cm Hsub 2O in another 20 rabbits. Histologic findings of the liver was compared with microcholangiographic findings. The results were as follows : 1. In microcholangiography, interlobular bile ducts and ductules were well noted, but bile canaliculi were ot visible. 2. After extrahepatic bile duct ligation, ductules and small interlobular bile ducts were tortuously dilated and proliferated. 3. Microbarium was regurgitated into hepatic sinusoids from a portal tract due to rupture of interlobular bile ducts or d ctules, and this was observed only in limited portions of sample tissue sections, but could be found in most of 40 rabbits. From the above results, the morphology of intrahepatic microbiliary system and its change after extrahepatic bile duct obstruction could be radiologically observed with microcholangiography, so this technique could be used for an experimental study about the biliary system.