Objectives: This study focused on the population structure of OXA-23-producing Acinetobacter baumannii clinical isolates from Rio de Janeiro, Brazil. Methods: The analysis included several genomic typing methods, including PFGE, two multilocus sequence typing (MLST) schemes, sequence group (SG) determination and blaOXA-51-like sequencing. The genomic context of the blaOXA-23 gene was also evaluated using I-CeuI hybridizations and PCR assays. Results: Congruent clustering was obtained revealing four lineages. In accordance, four new sequence types (STs) (ST131, ST132, ST133 and ST134) were obtained with the MLST-OD scheme (associated with the Oxford Database) and four (ST79, ST15 and two new allelic profiles) with the MLST-IP scheme (developed by the Institute Pasteur). Four SGs (SG1, SG4 and two new profiles) were identified, allowing the association of 70% of the isolates with European clone II. blaOXA-51-like sequencing revealed the presence of blaOXA-66, blaOXA-69, blaOXA-95 and blaOXA-132. Conclusions: Identification of new STs together with new SG profiles are findings suggestive of a local diversity hotspot that is worth exploring.2030-01-01