Susceptibility of 105 strains of bacteroides species (including 82 strains of B. fragilis, 8 strains of B. distasonis, 5 strains of B. thetaiotaomicron, 4 strains of B. vulgatus, 3 strains of B. ovatus and 3 other strains) isolated from patients to chemotherapeutic agents was determined by an agar dilution technique. Good to excellent inhibition rates (75--100% of strains) were found for carbenicillin, ticarcillin, piperacillin, apalcillin, minocycline, chloramphenicol, thiamphenicol, rifampicin, erythromycin, clindamycin, and lincomycin.