Plesiomonas shigelloides is an oxidase-positive, fermentative, gram-negative rod currently classified as a member of the family Vibrionaceae. P. shigelloides has been implicated as the causative agents of gastroenteritis as well as extraintestinal infections such as septicemia, neonatal meningitis, cellulitis, and cholecystitis. Septicemia due to P. shigelloides is very rare but is severe and has been associated with a high mortality rate. We report a case of septicemia caused by P. shigelloides in a 66-year-old male with diabetes mellitus who had diagnosed as liver cirrhosis 7 years before. (Korean J Clin Microbiol 2001;4(2):142-145)