A case of primary sclerosing cholangitis (PSC) is reported. A 16 year-old female developed right hypochondralgia and nausea without jaundice. Examination on admission showed elevation of SGOT, SGPT, Al-P, gamma-GTP and LAP activities, but T-Bil, AFP and CEA were within normal limits. Peripheral eosinocytes increased by 10%, and tests for HBsAg, antiHBs, antimitochondrial antibody and anti-smooth muscle antibody were all negative. ERCP revealed a narrowing of the proximal portion of the common the hepatic duct, and beading of the intrahepatic bile ducts. Liver scintigram and CT revealed no tumors in the liver, biliary tract or pancreas. Laparoscopy showed a smooth liver without swelling and a slightly swollen gallbladder. Histologically, the liver biopsy specimen showed ductal proliferation of small interlobular bile ducts and periductal fibrosis. No bile plugs, granuloma or distinct cholangitis were observed. No abnormal findings, including evidence of inflammatory bowel disease, were detected by barium enema. At present, one year after discharge, although her symptoms and liver function test abnormalities continue, she has been attending high school. Although 58 cases of PSC have been reported in Japan, juvenile cases occurring before the third decade number only 3 including ours.