The spread of OXA-24/OXA-40 (OXA-24/40)-producing Acinetobacter spp. in the Iberian Peninsula has been strongly influenced by clonal expansion, but the role of horizontal gene transfer has scarcely been explored. bla(OXA-24/40)-carrying plasmids and genetic environments were characterized in representative (n = 15) Acinetobacter species clinical isolates (obtained between 2001 and 2007) by Acinetobacter baumannii PCR-based replicon typing, sequencing, hybridization, and restriction fragment length polymorphism. Besides the identification of bla(OXA-24/40) within the chromosomes of some isolates, the circulation of common bla(OXA-24/40)-carrying plasmids (30-kb repA_AB; 10-kb aci2) and genetic backbones among Acinetobacter spp. was demonstrated.