Members of the genus Acinetobacter are considered among the important microorganisms incriminated in causing nosocomial infections. This genus is faced with many problems, one of them is its natural ability for acquiring drug resistance genes and virulence factors, with the appearance of Acinetobacter species showing resistance to the carbapenems, particularly imipenem.The aim of this work is to establish phenotypic methods for identification of A.baumannii in routine work, study the genomic diversity among carbapenem susceptible and non-susceptible A.baumannii by a molecular technique namely (rep-PCR) and to demonstrate its usefulness in source tracing of nosocomial outbreaks due to A.baumannii.Results showed the high percentage of imipenem-resistance among Acinetobacter species (62%) and the presence of a predominant clone in Cairo university hospitals detected by Rep-PCR technique.