Acinetobacter spp. are increasingly important nosocomial pathogens and are capable of rapid adaptation to the hospital environment. National surveillance of nosocomial infection in Japan from July 2000 to June 2001 showed that 1.5% of blood-stream infections has occurred by Acinetobacter spp. The greatest impact of Acinetobacter has been a causative agent of nosocomial pneumonia, particularly ventilator-associated cases. Recent trends indicate increasing antimicrobial resistance of Acinetobacter isolates, posing a serious threat to hospitalized patients. Especially, carbapenem-resistance including muti-resistant metallo-beta-lactamase producing isolates has been identified in Japan and other countries. Hand-washing policy and practices with daily decontamination of medical-devices or hand-contact environment should control nosocomial infection by Acinetobacter.