Acinetobacter baumannii is an opportunistic pathogen that causing nosocomial infections. The microorganisms can be developed resistance to antimicrobials very quickly by different mechanisms. Infections defend by MDR strains, caused require long-term hospitalization high morbidity and mortality. Tigecycline is one of the few antimicrobials which have activity against MDR A. baumannii strains. In Meta-analyzes and clinical study reported that a rising risk of mortality in tigecycline-treated patients due to an increase in resistance of these strains. In our study, we aimed to compare the MICs values of tigecycline and determine the resistance rates of tigecycline against to MDR A. baumannii strains in 2011 and 2015. Tigecycline MIC values of 200 A. baumannii isolates were determined by the broth microdilution method. Final concentrations were prepared as 16μg/ml to 0.06μg/ml. Tigecycline MICs breakpoint values comments on breakpoint values of Enterobacteriaceae that have been proposed by FDA. In 2011, tigecycline values of MIC50 and MIC 90 found 0.5μg/ml, 1μg/ml, respectively against to MDR A. baumannii strains. In 2015, tigecycline values of MIC50 and MIC90 found 1μg/ml, 4μg/ml, respectively. In 2011 the 4%, while in 2015, 16% of A. baumannii strains tigecycline MICs were determined over 2μg/ml. and that this was interpreted as the resistance. Tigecycline can be still use as an alternative antimicrobial for treatment of A. baumannii strains, especially in our hospitals intensive care units. However, to avoid the development of resistance against tigecycline, we should prevent the irrational use of antibiotics. The implementation of treatment should be based on antimicrobial susceptibility test results.