Background and Objectives: A. baumannii is a cause of various infections with significant morbidity and mortality in the world. The aim of this study was to determine infection rate and antimicrobial susceptibility of A. baumannii in an Iranian tertiary care Hospital.
 
Materials and Methods:
 This study was performed on 166 positive blood cultures for A. baumannii, received from different wards of Imam Hospitals complex in Tehran, during two years. Disk diffusion method was used to survey several antibiotics resistance. Data were analyzed by spss software, chi square test.
Results: A. baumannii was resistant to imipenem (26.9%), gentamicine (32.2%), carbenicillin (36.4%), cephotaxime(41.7%), ampicillin (66.7%), amikacine (69.4%), ciprofloxacin (74.3%), cotrimoxazol (86.3%),piperacillin (91%), Ceftriaxone (92.5%), cefixime (99.2%), amoxiclave  (100%), cefepime(100%), ceftazidime (100%). ICUs (50.6%) and Pediatrics Wards (2.4%) were the most and the least frequent wards in which A. baumannii were isolated.
Conclusions: Due to antibiotic resistance pattern change among A. baumannii and its consequences, it is recommended to control infection associated risk factors as well as further researches aiming identification of different of patterns in resistance and sensitivity to antibiotic.