Twelve strains of multi-resistant Corynebacterium jeikeium isolated during a one year period in a surgical unit in Innsbruck were analyzed with regard to their plasmid content, antibiotic susceptibility, and the use of ribosomal ribonucleic acid (rRNA) to probe restriction fragment length polymorphism (RFLP). Plasmids were detected in five of the strains. Southern blotting of genomic DNA digested with HindIII or PvuII and hybridized with a biotin-labelled cDNA probe derived from total rRNA revealed characteristic banding patterns. Seven of the 12 strains showed similar RFLP profiles, consistent with them being related epidemiologically. The minor changes in RFLP profiles observed in these seven strains suggest that Corynebacterium jeikeium may be subject to genetic drift over a relatively short time span. Strains from other sources, included for comparison, differed markedly from those from Innsbruck. Patterns of antibiotic susceptibility which appeared not to be plasmid encoded, correlated broadly with RFLP profiles. This study suggests that strains of Corynebacterium jeikeium may be transferred between hospital patients.