The emergence of multiple drug-resistant (MDR) Acinetobacter baumannii strains has become a global problem. This study aimed to evaluate the occurrence of antibiotic resistance and to investigate the presence of antibiotic resistance determinants among A. baumannii isolates obtained from hospitalized patients in Iran. This cross-sectional study was performed on 92 A. baumannii isolates in the years 2015-2016. Antimicrobial susceptibility testing was carried out by the disk diffusion method. The presence of antibiotic resistance determinants was detected by the PCR method. All the A. baumannii isolates were resistant to tested carbapenems, fluoroquinolones and sulfonamide agents, and susceptible to polymixins. Of the isolates 92.4% were extensive drug-resistant (XDR) and 7.6% were MDR. PCR screening for the presence of integron genes revealed that class 1 integron presented in 46.7% of isolates and class 2 in 18.5% isolates. Of the investigated antibiotic resistance genes, bla vim, bla imp, bla spm, sul1 and sul2 were positive in 75%, 12%, 12%, 47.8%, and 67.4% of isolates, respectively. The high prevalence of metallo-beta-lactamase (MBL) and sul genes in our results may indicate the importance of these genes in the dissemination of carbapenem- and sulfonamide-resistant A. baumannii isolates. Rational and restricted prescription of carbapenems may be an effective way to minimize the emergence and spread of MBL-harboring strains.