In the last two decades, there has been a remarkable rise in the instances of nosocomial infections associated with antibiotic-resistant Acinetobacter baumannii. The aimed of this study to determine the antibiotic resistance patterns and genetic relationship among isolates of carbapenem-resistant A. baumannii (CRAB) isolated from the clinical specimens of various inpatients. A total of sixty clinical isolates of A. baumannii were collected during February to September 2014 from King Fahd Hospital of the University (KFHU) in Khobar, Saudi Arabia. Antimicrobial susceptibility was tested using the Vitek 2 system and the minimum inhibitory concentrations (MICs) were estimated following the guidelines of the Clinical and Laboratory Standards Institute. Molecular epidemiological analysis of carbapenem-resistant A. baumannii (CRAB) was carried out by using enterobacterial repetitive intergenic consensus (ERIC-PCR). All of tested clinical isolates of A. baumannii in this study were associated with nosocomial infections and the highest rates of A. baumannii isolates were from wound swabs (23.3%) and transtracheal aspiration (20%). All of the 60 analyzed strains of A. baumannii in this study were classified as extensively drug-resistant (XDR), and the rates of antibiotic resistance against imipenem and meropenem were 93.3% and 96.6% respectively, while just 6.6% of strains were resistant to tigecycline. All 60 XDR A. baumannii isolates were sensitive only to colistin. The genotypic analysis of CRAB was performed by enterobacterial repetitive intergenic consensus (ERIC-PCR). ERIC-PCR able to discriminate the CRAB strains into four distinct clusters (A, B, C, and D) with genetic similarity ranged from 82.5 to 100%.