BACKGROUND/AIMS: Intrahepatic duct strictures are usually caused by intrahepatic duct stones and cholangitis. However, focal strictures of the intrahepatic duct unrelated to intrahepatic stones often pose diagnostic problems. This study was undertaken to prospectively evaluate the usefuless of percutaneous transhepatic cholangioscopy in patients with a focal intrahepatic duct stricture and no evidence of a stone. METHODS: Twenty two patients with a focal stricture of the intrahepatic duct not related to intrahepatic stones were included. Percutaneous transhepatic cholangioscopic examination including procurement of a biopsy specimen was performed after percutaneous transhepatic biliary drainage. RESULTS: A histopathologic diagnosis was obtained in all patients (10 adenocarcinoma, 1 squamous cell carcinoma, 2 hepatocellular carcinoma, 2 adenoma and 7 benign strictures). Of the 10 patients with bile duct adenocarcinoma, 9 underwent surgery and a curative resection was possible in 8 patients (89%). Six patients (67%) had early-stage bile duct cancer in which the cancer invasion was limited to the mucosa or fibromuscular layer and there was no evidence of lymph node metastasis. CONCLUSIONS: Percutaneous transhepatic cholangioscopy in patients with focal stricture of the intrahepatic duct unrelated to choledocholithiasis seems to be very useful for the differential diagnosis including the detection of early bile duct cancer.