Two hundred and eighty-two strains of Pseudomonas aeruginosa were isolated from patients at the Department of Obstetrics and Gynecology, Gifu University School of Medicine, between 1998 and 2000, and among them, 27 imipenem (IPM)-resistant strains of P. aeruginosa (27/282; 9.6%) were isolated from urine, exudate from surgical wounds, and ascites. Seven of the 27 IPM-resistant P. aeruginosa strains were positive (25.9%) for the bla (imp) gene determined by a polymerase chain reaction (PCR) method, and 4 of them were positive for the aac (6')-Ib gene. No strain of P. aeruginosa had both the bla (imp) and aac(6')-Ib genes. Pulsed-field gel electrophoresis (PFGE) patterns indicated the nosocomial spread of IPM-resistant P. aeruginosa. The presence of IPM-resistant P. aeruginosa carrying the bla (imp) gene might be implicated in possible spreading and outbreaks, and screening for bla (imp)-positive P. aeruginosa, therefore, might be necessary for protection against nosocomial infection.