Acinetobacter baumannii (A. baumannii) is one of the leading causes of morbidity and mortality in patients who are in critical condition in hospitals and especially in intensive care units (ICU). Long time considered a bacterium with low virulence, A. baumannii has more recently become a cause for major concern in clinical practice due to its high level of antimicrobial resistance. The extend of infections with Acinetobacter baumannii in ICU is caused by multiple factors, such as mechanical ventilation, invasive procedures, the use of a large number of broad spectrum antibiotics and transmission through the hands of medical staff In this study we evaluated the resistance to antibiotics of 213 non-duplicated strains of A. baumannii isolated in the bacteriology laboratory of the "Marius Nasta" lnstitute of Pneumophtisiology (IPMN) from January 2012 to December 2013. These strains originated from patients in medical wards (56), ICU (143) and surgery (14). Strains identification was performed by classical methods on multitest media and with API kits (Bio Merieux). The antibiotic sensitivity was performed on Mueller-Hinton media in accordance with CLSI2013. Analysis of the resistance to antibiotics was the following: carbenicilin (87.3%), ceftriaxone (87.3%), cefoperazone with sulbactam (84.9%), ceftazidime (79.3%), carbapenems (imipenem and/or meropenem--75.1%), fluoroquinolones (ciprofloxacin and/orlevofloxacin--73.7%), cefepime (66.6%), piperacilin with tazobactam (62.4%), amikacin (50.2%), netilmicin (45%), gentamicin (42.7%) and tobramycin (35.6%). In our study, we only found two strains of Acinetobacter baumannii with resistance to colistin and 70 (32.8%) strains sensitive only to colistin, but resistant to all other antibiotics tested. A. baumannii is a pathogen with rapid spread and extended resistance to even newer antimicrobial agents. Due to its ability to survive in the hospital environment, A. baumannii has the immense potential to cause nosocomial infections. We did not find significant differences between the antibiotic resistance of strains isolated from ICU patients and those obtained from medical or surgical wards. This study has also shown that there is a high number of A. baumannii strains with resistance to almost all antibiotics tested, notably with the exception of colistin, wich therefore becomes the antibiotic of choice in the treatment of these infections. The marked increase in the number of multidrug resistant A. baumannii strains highlights the need for a more rational use of broad spectrum antibiotics, as well as for an immediate review of infections control protocols, so as to limit the spread of this pathogen.