A 57-yr-old male on long-term steroid therapy presented with hematemesis, fever, and a retroperitoneal fluid collection. Hemobilia was diagnosed, but the cause was not identified by ERCP, computed tomography, or angiography. Peroral cholangioscopy revealed multiple biliary ulcers. Cholangioscopic biopsies diagnosed cytomegalovirus (CMV) infection. Intravenous ganciclovir therapy was initiated, and was associated with cessation of bleeding. Biliary CMV disease is rare in HIV-negative persons, but should be considered in a patient with unexplained hemobilia. Cholangioscopy may be useful for diagnosis.