This study was performed to compare the mortality associated with carbapenem-resistant Acinetobacter baumannii (CRAB) and carbapenem-sensitive A. baumannii (CSAB) infections, to identify potential risk factors for CRAB infections, and to investigate the effects of potential risk factors on mortality in CRAB and CSAB patients. This retrospective case-control study was conducted in a university hospital between January 1, 2005 and December 30, 2006. One hundred and ten patients with CRAB and 55 patients with CSAB infection were identified during the study period. The mortality rate was 61.8% and 52.7% in CRAB and CSAB cases, respectively (P = 0.341). In CRAB cases, the risk factors for mortality were identified as intubation (odds ratio [OR], 3.3; 95% confidence interval [CI], 1.0-10.1; P = 0.042) and high APACHE II score (OR, 1.2; 95% CI, 1.1-1.3; P = 0.000), by multivariate analysis. Previous use of carbapenem (OR, 6.1; 95% CI, 2.2-17.1; P = 0.001) or aminopenicillin (OR, 2.5; 95% CI, 1.2-5.1; P = 0.013) were independently associated with carbapenem resistance. Although the mortality rate was higher among patients with CRAB infections, this difference was not found to be statistically significant. Previous use of carbapenem and aminopenicillin were found to be independent risk factors for infections with CRAB.