The purpose of this study was to determine the effect of various disinfectants and antiseptics on nosocomial bacteria. The effects of six disinfectants (ethyl alcohol, sodium hypochlorites, povidone-iodine 10%, chlorhexidine gluconate 4%, sacti-med, glutaraldehyde 2%) on 46 bacteria (nine Acinetobacter spp., nine Stenotrophomonas maltophilia, nine Pseudomonas aeruginosa, nine Escherichia coli, five methicillin-resistant Staphylococcus aureus, five methicillin-susceptible S. aureus) isolated as agents of hospital infections and on three ATCC standard strains (P. aeruginosa 27853, E. coli 25922, S. aureus 6538) with different consantrations (50, 70, 95 % for ethyl alcohol and 1/10, 1/100, 1/1000 dilütions of the others) and different exposure times (1, 2, 5, 10, 30 min) by qualitative suspension test method were studied. The most effective disinfectants were ethyl alcohol and chlorhexidine gluconate 4% and the least was glutaraldehyde 2%. Pseudomonas aeruginosa was the most resistant bacterium. It is concluded that every hospital should determine the disinfectant effective on the current microorganisms to control hospital infections, because the susceptibility of bacteria isolated from various hospitals can be different.