Acinetobacter baumannii is an extensively drug resistant pathogen, ranked among six bacterial species responsible for nearly three quarters of deaths associated with antimicrobial resistance (AMR) worldwide [1]. Pan-antibiotic resistant isolates predominately belong to established clonal lineages, and can exhibit variation in the type of capsular polysaccharide (CPS) on the cell surface, with some types associated with increased virulence and/or poorer patient outcomes. The specific combination of genes at the CPS biosynthesis K locus (KL) in the chromosome is therefore an ideal epidemiological marker used in conjunctional with standard multi-locus sequence typing to delineate clonal isolates. However, the association between KL and clones distributed on a global scale is largely unknown. A recent update to the international database for A. baumannii KL typing using a pool of 8994 public genome sequences presented an ideal opportunity to explore the KL diversity amongst prominent clonal groups [2]. Using the same pool, genome assemblies were subjected to MLST typing using the Institut Pasteur scheme to determine sequence types (STs) and the available metadata was extracted to assess diversity in geographical region, isolation source and collection dates. Eight major clonal groups accounted for 79.2% of genomes studied and each clone was found globally distributed and associated with an array of clinical, environmental, and animal samples. Analysis of KL frequency highlighted lineages with surprising levels of KL variation. For example, the major global clones, ST2 (n= 4033) and ST1 (n= 450), had 80 and 21 KL, respectively. However, KL diversity in ST25 (n= 209) was greater than that observed for clones with 2-fold higher representation (i.e. ST1), with 35 distinct KL. Though several KL were found in more than one clone, overrepresented KL were different in each clone with some prominent types linked to increased virulence. Distribution of KL, particularly in under studied clones such as ST25, therefore requires further research to identify selective pressures driving CPS diversification.