The taxonomic position of a group of 16 Moraxella catarrhalis-like strains, isolated mainly from dogs, was examined by using morphological tests, biochemical tests, serology, ribotyping with oligonucleotide probes, polymerase chain reaction typing of the 16S rRNA gene and the 16S-23S rRNA gene spacer region, polyacrylamide gel electrophoresis of total proteins, fatty acid profiles, moles percent G+C, dot spot and in-solution DNA-DNA hybridizations, and DNA-rRNA hybridizations. It was found that these organisms constitute a distinct cluster within the genus Moraxella. Since they differ genotypically as well as phenotypically from previously described Moraxella species, a new species, Moraxella canis, is proposed to accommodate these isolates. The type strain is LMG 11194 (= N7 = CCUG 8415A).