Teikyo University Hospital reported an outbreak of multidrug-resistant Acinetobacter baumannii (MDRAB) to the local public health department in 2010. The number of inpatients with MDRAB including asympto- matic carriers was 58 between August 2009 and September 2010. The way to tackle infection control issues has been comprehensively revised since this event in our hospital. The change could not have been achieved by a single department, such as the Department of Infection Control and Prevention or the Central Laboratory alone. Rather, collaboration among every department in the hospital was necessary. Although the impact of the outbreak on our hospital was enormous, it elucidated various clues to improve hospital man- agement regarding not only infection control but also safety management. [Review].