Selective internal radiation (SIR) therapy using 90yttrium microspheres is effective for treating selected cases of unresectable liver malignancies with little morbidity. We herein report two cases illustrating a very rare complication of SIR. A 68-year-old patient with inoperable recurrent hepatocellular carcinoma received one treatment of SIR with 90yttrium microspheres and 4 months later presented with obstructive jaundice. Percutaneous transhepatic cholangiography revealed diffusely dilated intrahepatic ducts with multiple biliary strictures. Hepatic angiography showed normal hepatic arterial branches with no evidence of vascular insufficiency. Liver biopsy finally revealed cholestasis, cholangitis, and fibrosis, consistent with radiation-induced damage. Another 56-year-old patient with unresectable colorectal liver metastases presented with cholangitis 4 weeks after SIR. Ultrasonography showed no biliary dilatation, and endoscopic retrograde cholangiopancreatography demonstrated a normal biliary tree. Liver biopsy subsequently confirmed radiation-induced cholangitis.