The antimicrobial susceptibility of 93 Acinetobacter baumannii complex isolates from clinical specimens collected nationwide between May and October 2009 were measured by microdilution antimicrobial susceptibility testing based on CLSI M100-S20. Beta-lactamase genes, including classes B and D and ISAbal in meropenem nonsusceptible, including intermediate or resistant isolates, were detected using PCR. Rates of isolates nonsusceptible to meropenem were 18%, to ciprofloxacin 41% and to amikacin 14%. L7-L8: The rate of multidrug-resistant Acinetobacter (MDRA) isolates which were resistant to all 3 antimicrobial agents was 4.3%. MDRA isolates were classified into ST92 by multilocus sequence typing. No metallo-beta-lactamase producer was seen among the 17 meropenem nonsusceptible isolates. The blaoxa-51-like carbapenemase gene and ISAbal were detected in all 17 isolates. ISAba1 upstream presence of the blaOXA-51-like gene was observed in 7 of 17 isolates and the blaOXA-23 like gene in 5 of 17. Consistent with overseas reports, our results confirm the existence of MDRA isolates and isolates harboring OXA carbapenemase genes in Japan. While resistance rates were lower than reports elsewhere, it is clear that resistance trends must be carefully monitored.