Colistin and tigecycline are the only therapeutic options for extensively drug resistant Acinetobacter baumannii (XDR-AB), but there is little comparative study. This retrospective observation study evaluated two-colistin and tigecycline-antibiotics profiles like treatment success rate, negative conversion rate, the length of hospital stay, intensive care unit (ICU) stay and antibiotics use, mortality rate during hospital stay and adverse event rate, based on the medical record of XDR-AB positive patients who were treated at least 5 d with those intravenous antibiotics. Treatment success rate of colistin (n=39) and tigecycline (n=16) were not different: 48.7% and 43.8%, respectively (p=0.737), though negative conversion rate was significantly higher in the colistin group: 46.2% against 12.5% (p=0.049). There was no statistically significant difference in mortality rate between two groups during hospital stay (43.6% vs. 56.3%, p=0.393). There were no significant differences in the following parameters: the median length of hospital stay (46.0 d vs. 72.5 d), the median length of intensive care units stay (26.0 d vs. 27.0 d), the median length of antibiotics use (15.0 d vs. 13.0 d). The colistin group showed serum creatinine elevation (defined as elevation more than 2.0 mg/dL and 50% increase from the baseline) as 43.6% when compared with 12.5% of the tigecycline group (p=0.028). As a therapeutic option of XDR-AB, colistin showed significantly better negative conversion rate than tigecycline with more frequent nephrotoxic prevalence, and treatment success rate and mortality rate were not different from both antibiotics groups.