The aim of this study was to evaluate the susceptibility to antibiotics and quaternary ammonium disinfectants of Acinetobacter baumannii strains isolated from patients with nosocomial infections and the environment of the ICU and Neonatal Service (NS) at the Caracas University Hospital. Resistance to 15 antibiotics was determined. To evaluate the disinfectant resistance phenotypes tests recommended by the AOAC were used. ERIC-PCR and REP-PCR were used for genotyping. We analyzed 74 A. baumannii, 14 and 1 from ICU and NS patients, respectively; and 42 and 17 from its corresponding environments. 44.6% of the isolates showed resistance to at least 7 antibiotics. 54% of isolates tested exhibited the resistance phenotypes to the quaternary ammonium hospital disinfectant evaluated. 73% of the isolates from patients were closely related clones, 28.8% of the environmental isolates were grouped in 7 indistinguishable clones groups. The multiple antibiotic and disinfectant resistance profiles and the presence of related bacterial clones demonstrate the need for antibiotic usage surveillance and alternative cleaning methods in this hospitalCDCH, Fonacit