Methodological differences makes it difficult to compare results of antimicrobial susceptibility testing obtained in Russia and in other regions. During the period from October 1993 to May 1994 susceptibility of 1296 isolates of bacteria was investigated according to NCCLS standards by the broth microdilution method. The order of activity of antibiotics against Gram-negative bacteria based on percent of susceptible strains from common hospitals were: amikacin (98%) > ciprofloxacin (93%) = imipenem (93%) > cefoperazone/sulbactam (92%) > ceftazidime (89%) > ceftriaxone (81%) > cefotaxime (80%) > cefoperazone (77%) > gentamicin (71%) > ampicillin/sulbactam (51%) > cefazoline (45%) > ampicillin (25%). The order of activity against strains from teaching hospitals was similar but the percent of susceptible strains was 10-20% less for the majority of antibiotics. The susceptibility level of Gram-negative isolates from Moscow teaching hospitals is lower than from Northern America and Europe. Ampicillln/sulbactam and cefoperazone/sulbactam, as well as other cephalosporins, demonstrated high activity against methicillin-susceptible staphylococci and penicillin-susceptible pneumococci. B-lactams/beta-lactamase inhibitor combinations were active against 100% strains of anaerobic bacteria.