Raoultella ornithinolytica is a Gram-negative aerobic bacillus reclassified in the new genus from the Klebsiella species based on new genetic approaches; however, human infections caused by R. ornithinolytica are rare. We herein report three cases of R. ornithinolytica bacteremia associated with biliary tract infections in cancer patients. R. ornithinolytica can be a causative pathogen of biliary tract infection in cancer patients.