Extrahepatic cholangiocarcinoma is often clinically challenging to diagnose. Even multidisciplinary approaches which include computed tomography, magnetic resonance imaging, and endoscopic retrograde cholangiography are unsatisfactory in some cases, especially with biliary stricture. Percutaneous transhepatic cholangioscopy (PTCS) with its direct visualization for biopsy appears to be a promising technique for detecting cholangiocarcinoma at an early stage. We report a case of adenocarcinoma in situ of the distal common bile duct (CBD) that was confirmed by PTCS. This case suggests the useful role of PTCS in the differential diagnosis of a distal CBD obstruction, particularly when other diagnostic modalities do not provide definitive information.