Acinetobacter baumannii is often implicated in hospital outbreaks in Tunisia. It's a significant opportunistic pathogen associated with serious underlying diseases such as pneumoniae, meningitis and urinary tract infections. The aim of our study was to evaluate its degree of endemicity and its antibiotic resistance evolution essentially in the unit care where its isolation was predominant (57%). This study used 3 methods: antibiotyping, RAPD using 2 primers VIL 1, VIL5 and PFGE with ApaI restriction enzyme. The presence of integron1 and 2 was also studied. Antibiotyping showed that 92% of patients were resistant of all ß- lactams (except Imipenem) and that the resistance to Imipenem occurred in 47% of cases. RAPD profiles obtained with the 2 arbitrarily primers VIL1 and VIL5 gave respectively 5 and 4groups and PFGE fingerprinting patterns revealed 22 different pulsotypes. Integron 1 was present in 25% of unrelated strains and type 2 integron was not detected in any of the studied strains. Among 204 strains, multiple and heterogeneous groups were detected with the genomic studies. In addition, any correlation was obtained with the antibiotyping results. These findings demonstrate the endemic status of A. baumannii in our hospital and the persistence of a large number of multiresistant strains in the unit's care. When outbreaks of A. baumannii occur, it's essential to develop restricted hygiene procedures and a serious surveillance of critical units such as ICU for very ill patients.