Y. pseudotuberculosis caused disease primarily in rodents, particulary guinea pigs, but the human infections have recently been increasingly recognized. There are two clinical patterns of human infection with Y. pseudotuberculosis. The more common form presents as mesenteric lymphadenitis, the second form occurs less commonly, presents an acute septic course and usually end fatally. There have been two reported cases of the septic form in Korean literature and we here report a case of Y. pseudotuberculosis septicemia. A 67-year-old male patient with underlying liver disease presented mild abdominal pain for 5 months followed by abrupt fever and disorientation 5 days prior to admission. the organism isolated from blood culture showed quitecharacteristic morphology on blood agar plate after 36 hours of incubation; raised colones with opaque center and lighter margin with serration. The biochemical properties of the isolated organisms were consistent with other reports. Antibiotic susceptibility test showed sensitivity to chloramphenicol, ampicillin, cephalothin, tetracycline, kanamycin, amikacin, carbenicillin, and tobramycin.