A prospective study between September 2008 and April 2010 were performed at the intensive care unit of Bach Mai hospital. Of the 53 isolates of Acinetobacter baumannii obtained from infected patients, 52 (98.1 percent) were multidrug resistance. The percentage of Acinetobacter baumannii isolates resistant to imipenem and meropenem were 84.9 percent and 86.8 percent, respectively. High-level resistance to piperacillin (MIC or = 512), ceftazidime (MIC, 128 -512), and ciprofioxacin (MIC, 32 -128) were exhibited in the obtained Acinetobacter baumannii isolates. A total of 46 isolates belonging to 6 major clusters (A, B, C, D, E and F) with DNA pattern similarity ranged from 80.0 percent to 96.1 percent. Clone D was the most predominant and had been detected through the entire 8-month study period. These findings suggest important areas for synchronous implementation of infection control interventions to prevent nosocomial Acinetobacter baumannii infections at the intensive care unit in Bach Mai hospital.