The family Enterobacteriaceae are the most frequently encountered microorganisms in the clinical microbiology laboratory and its classification is based primarily on the determination of the presence or absence of different enzymes coded by the genetic material of the bacterial chromosome. In 1981, Farmer et al. proposed Kluyvera as a new genus in the family Enterobacteriaceae with two species K. ascorbata and K. cryocrescens on the basis of DNA-DNA hybridization, biochemical reactions and antibiotic susceptibility. The authors experienced 3 cases of Kluyvera, formerly reported as unidentified or Citrobacter sp., during the period of 1 year form Jan. To Dec. 1981. The specimens and relevant clinical features are bile with gall stone and chronic cholecystitis associated with acute pancreatitis, umbilical discharge with neonatal hyperbilirubinemia and sputum with pneumonia associated with pulmonary tuberculosis, respectively. These isolates were considered clinically significant on the basis of chart review. They are susceptible to commonly used antibiotics such as amikacin, dibekacin, gentamicin, sisomycin and tobramycin. The patients were treated with amikacin, chloramphenicol and gentamicin and discharged with well condition.