Five highly amikacin-resistant Acinetobacter baumannii isolates were collected at a medical center in Pennsylvania. The aminoglycoside resistance was due to the production of the 16S rRNA methylase ArmA. Two of the isolates coproduced OXA-23 beta-lactamase and were highly resistant to carbapenems as well. The isolates were genetically closely related by pulsed-field gel electrophoresis.