An epidemiological survey on 417 sample from ICU patients, was carried out from January '97 to December 98 to verify the epidemiology of bacteria responsible for nosocomial infections and to monitor the susceptibility patterns to antimicrobial drugs during this period. Microbiological cultures were positive in 47.7% of the samples. P. aeruginosa was the most frequent pathogen, followed by Staphylococcus aureus, Candida spp, coagulase-negative staphylococci, E.coli, with a clear prevalence of Gram-negative over Gram-positive isolates. The evaluation of the antibiotic susceptibility profile of this bacterial pathogens suggests the importance of a costant epidemiological surveillance in ICU.