Background: The aim of this study was to determine the frequency of blaNDM, blaPER, bla VEB, blaIMP and bla- VIM type genes among A. baumannii isolates from hospitalized patients in Milad and Loghman Hakim hospitals, Tehran- Iran from 2012 to 2013.rnMethods: This study was conducted on 108 A. baumannii isolates collected from Milad and Loghman Hakim hospitals in Tehran, Iran. Antibiotic susceptibility tests were performed by Kirby-Bauer disc diffusion and Broth micro dilution methods according to CLSI guidelines. The frequency of MBL (metallo-beta-lactamase) and ESBL (extended spectrum- beta-lactamase) producers were evaluated by CDDT (Combined disk diffusion test). The blaNDM, bla- PER, blaVEB, blaIMP and blaVIM genes were detected by PCR and sequencing methods.rnResults: The resistance of A. baumannii isolates to the tested antibiotics were as follow: 103 (95.4%) to ceftazidime, 108 (100%) to cefotaxime, 105 (95.7%) to cefepime, 99 (91.7%) to imipenem, 99 (91.7%) to meropenem, 87 (80.6%) to amikacin, 105 (97.2%) to piperacillin, 100 (92.6%) to ciprofloxacin, 103 (95.4%) to piperacillin/tazobactam, 44 (40.7%) to gentamicin, 106 (98.1%) to ampicillin/sulbactam, 106 (98.1%) to co-trimoxazole, 87 (80.6%) to tetracycline and 1 (1.8%) to colistin. Using combined disk diffusion test, it was found that out of 108 cefotaxime-non-susceptible A. baumannii strains, 91 (84.2%) were ESBL producers and out of 99 imipenem non-susceptible A. baumannii strains, 86 (86.86%) were MBL producers. The prevalence of blaPER-1 and blaVEB-1 genes among 91 of ESBL-producing A. baumannii isolates were 71 (78.03%) and 36 (39.5%), respectively. The prevalence of IMP-1 and VIM-1 genes among metallobeta- lactamase-producing A. baumannii isolates was 3 of 86 (3.48%) and 15 of 86 (17.44%) respectively and also confirmed for blaOXA-51 gene by PCR. Fortunately, blaNDM gene was not detected in isolates.rnConclusion: The prevalence of ESBLs and MBLs-producing A. baumannii strains is a major concern and highlights the need of infection control measures including prompt identification of beta-lactamase-producing isolates and antibacterial management.rn