A 69-year-old Japanese man was admitted to our hospital because of acute cholangitis with biliary obstruction. The cause of obstruction was either compression by a portal cavernoma or cavernous transformation. Multidetector row computed tomography (MDCT) and abdominal ultrasonography (US) revealed a portal cavernoma around the common bile duct. Magnetic resonance cholangiopancreatography (MRCP) and endoscopic retrograde cholangiography (ERC) demonstrated characteristic short, smooth narrowing of the bile duct. Endoscopic US and intraductal US demonstrated collateral vessels around the bile duct and were helpful for ruling out a neoplastic lesion. Thus, a combination of imaging modalities was useful for diagnosing this hepatobiliary complication, portal biliopathy.