Eighteen isolates of Puccinia menthae collected from Mentha × cordifolia (garden mint), M. × gracilis (Scotch spearmint), M × piperita (peppermint), M. × piperita ssp. citrata (eau-de-cologne mint) and M. spicata (spearmint) growing in two separate regions of Victoria, Australia, were tested for differences in pathogenicity on 33 clones from 13 species in Mentha and three species in related genera. Fifteen races were identified on the basis of host reactions. Two groups of rust, peppermint rust and spearmint rust, were clearly demarcated according to the original host of the isolate. Nine races were ascribed to the peppermint rust group and six races to the spearmint rust group.