Bacterial kidney disease (BKD), which results in significant mortality among wild and hatchery-reared salmonid fishes, is caused by the bacterium Renibacterium salmoninarum. Studies of this pathogenic bacterium include determination of the extent of genetic diversity over numerous strains within the species, which has important implications for disease treatment, taxonomic identification, serodiagnostics and vaccine development. The purpose of this study was to use multilocus enzyme electrophoresis (MEE) to determine the presence and mobility of enzyme activities for a representative number of R. salmoninarum isolates. The level of genetic diversity for the species could then be calculated.