In this study, bactericidal activity of widely used disinfectants and antiseptics (glutaraldehyde, laurylbispropylidentriamin 5 g and benzalkoniumchlorid 20 g, polyvinylpyrolidon iodine, benzalkonium chloride and sodium hypochloride) against some nosocomial bacterial isolates were investigated by qualitative and quantitative suspension test methods. One methicillin-resistant Staphylococcus aureus (MRSA), 6 multi drug-resistant Gram-negative hospital isolates (Escherichia coli, Pseudomonas aeruginosa, Enterobacter cloaca, Klebsiella pneumoniae, Citrobacter diversus, Serratia marcescens) and 3 standard strains of American Type Culture Collection (ATCC) bacteria (S. aureus, P. aeruginosa, E. coli) were tested against three different concentrations of disinfectants of which, manufacturer's recommended use-dilution, 1/2 and 1/4 of those recommended dilutions. All tested disinfectants were found effective in all three concentrations against nosocomial isolates in five minutes, by using both qualitative and quantitative suspension methods. When the test was repeated with albumine, bactericidal activities of disinfectants were found the same. Our findings showed that these disinfectants can be still used in safe for the sterilization in hospital, and routine disinfection protocols do not need to be alerted.