Brucella canis strains isolated from house dogs, stray dogs and beagles in breeding or experimental colonies were examined for their susceptibility to 38 antibacterial drugs by an agar dilution method. All of 90 strains tested were found to be highly susceptible to tetracyclines and aminoglycoside antibiotics. These were also susceptible to chloramphenicol, spectinomycin, rifampicin and sulfonamide. However, in these isolates, decreased susceptibility was found to cephalosporin antibiotics and nalidixic acid, and almost insensitivity to peptide antibiotics and cycloserine. On the other hand, 22 (24.4%) of 90 strains tested were found to be multiply resistant to macrolide antibiotics, some of penicillins, novobiocin and lincomycin. These multiple drug-resistant strains were isolated from stray dogs and beagles in various districts, indicating that the prevalence of such resistant strains is relatively wide-spread in dogs in Japan.