Bilophila wadsworthia is a recently recognized nonspore-forming anaerobic Gram-negative rod and is reported to be associated with various surgical infections. In the present study, the isolation rate of B. wadsworthia from surgical specimens and its antimicrobial susceptibilities were examined. Last 5 years, B. wadsworthia was isolated from 46 (5.2%) out of 884 specimens from the surgical abdominal infections. B. wadsworthia was most frequently isolated from secondary peritonitis such as perforated peritonitis, followed by postoperative peritonitis. There is no case of single isolation of B. wadsworthia. The rate of mixed infection with Bacteroides spp. (24.8%) was highest, followed by Escherichia coli (11.6%) and Enterococcus spp. (10.1%). Although B. wadsworthia was highly resistant to many beta-lactam antibiotics, clindamycin showed strongest activities with MIC90 of 1 microg/mL, followed by minocycline and ciprofloxacin with 4micro g/mL, and levofloxacin with 8 microg/mL, respectively.