AbstractWe studied 233 patients with biliary atresia seen between 1953 and 1985. Specimens of the extrahepatic bile ducts and liver which were taken at the time of corrective operation were examined histologically. We noted the presence of inflammation in the extrahepatic bile ducts, which confirmed in retrospect the necessity for early operation. The results of these studies are discussed in connection with the pathogenesis, pathophysiology and clinical features of this disease.