Activity of oxidation-reduction enzymes such as succinate dehydrogenase, peroxidase and catalase was studied in staphylococci isolated from healthy persons and patients as well as from the air and implements of medical institutions. The isolates were resistant either to antibiotics or to chloramine B or to the both. The results showed that development of resistance to antibiotics and chloramine B in the staphylococci was accompanied by a decrease in the activity of succinate dehydrogenase, peroxidase and catalase. In the strains resistant only to chloramine B the activity of the enzymes was practically at the same level as in the strains resistant only to antibiotics. In the strains resistant to both antibiotics and chloramine B, the activity of succinate dehydrogenase, peroxidase and catalase did not practically differ from that in the strains resistant either to antibiotics or to chloramine B.