Multidrug-resistant (MDR) Acinetobacter baumannii are emerging as important nosocomial pathogens. These organisms have a capacity for long-term survival in the hospital environment. The purpose of this study was to describe the course and control of an outbreak with MDR A. baumannii in a Belgian university hospital after transfer of two trauma patients from Greece. Wounds in both patients were colonised with MDR A. baumannii. Over an 11 month period from September 2004 to July 2005, carbapenem-non-susceptible A. baumannii (producing carbapenem-hydrolysing oxacillinase OXA-58) were isolated from 28 patients, despite early implementation of contact precautions. MDR A. baumannii was detected in routine clinical diagnostic samples from 26 patients and in screening specimens from an additional two patients. Twenty patients (71.4%) were colonised or infected during their stay in intensive care. Twenty-four (85.7%) respiratory samples were positive for MDR A. baumannii. Careful review of all procedures related to the respiratory tract did not identify a common route of transmission. Outbreak control required multiple interventions, including contact isolation of colonised and infected patients, monitoring the practice of personnel, screening of asymptomatic patients, use of isolation rooms and enhanced environmental disinfection. Introduction of single-use ventilator circuits was considered but the outbreak was controlled before implementation.