Antimicrobial susceptibilities of 23 strains of Desulfovibrio spp. were tested by Etest. Generally, Desulfovibrio spp. were highly susceptible to sulbactam-ampicillin, meropenem, clindamycin, metronidazole, and chloramphenicol: MIC(90)s of 6, 4, 0.19, 0.25, and 8 microg/ml, respectively. In addition, these strains generally showed high MICs to piperacillin and piperacillin-tazobactam. Desulfovibrio fairfieldensis (eight strains) was the species least susceptible to most agents, especially beta-lactams, and was the only species resistant to fluoroquinolones. Desulfovibrio desulfuricans strain Essex 6 isolates were less susceptible to beta-lactams than D. desulfuricans strain MB isolates.