In this paper we have analyzed random sample of 108 nosocomial infections at a surgical services of Clinical Center of University and a State Hospital in Sarajevo during april-september of 1992. The overall rate of nosocomial infections of postoperative wound was 69.45%. Gram negative bacterias were more frequently isolated then gram positive bacteria. Pseudomonas aeruginosa was detected at 20.37% of all wound infections, E coli and Klebsiella Sp. with 12.96%, and Staphylococcus pyogenes with 12.03%. Without a continuous germ control of the hospital flora no calculated antibiotic is possible. Pseudomonas has emerged as an important nosocomial pathogen and this suggest that the epidemiology of nosocomial infections differs from epidemics infections.