We describe an outbreak of multi-drug-resistant Acinetobacter baumannii (MRAB) that occurred in an intensive care unit (ICU) and a surgical ward from December 2003 to March 2004. Mapping patient movements on a timeline indicated that the outbreak was confined to these two areas. Investigation by the hospital's infection prevention service found that a possible source of spread was improper cleaning methods used on respiratory equipment. Pulsed-field gel electrophoresis analysis of available isolates indicated the presence of two distinct strains. One strain was seen in patients from the ICU and the other strain was seen in the surgical ward patients. Cleaning and environmental decontamination as well as staff education were implemented to halt further immediate spread. The deficiencies identified during the investigation were also resolved. The final outcome was the successful termination of this outbreak.