The in vitro susceptibility of 83 Corynebacterium group D2 strains and 44 Corynebacterium jeikeium strains to 12 antimicrobial agents was determined by an agar dilution technique using Mueller-Hinton agar supplemented with Tween 80 (0.025%). All strains of Corynebacterium group D2 were highly sensitive to fusidic acid, pristinamycin, teicoplanin and vancomycin (geometric mean MICs 0.047, 0.048, 0.338 and 0.396 mg/l respectively). Most of the strains were resistant to other antibiotics tested (ciprofloxacin, erythromycin, gentamicin, lincomycin, rifampin and tetracycline). However, a few strains were highly sensitive (MICs less than or equal to 0.2 mg/l). The overall pattern of susceptibility of 44 strains of Corynebacterium jeikeium was similar; the geometric mean MICs of fusidic acid, pristinamycin, vancomycin and teicoplanin were 0.234, 0.235, 0.557 and 0.652 mg/l respectively.