The recently proposed species Eubacterium minutum and Eubacterium tardun appeared to be similar from their published descriptions. The aim of this stud was to perform phenotypic and genetic analyses of strains of both species clarify their taxonomic position. The type strains of E. minutum and E. tardun exhibited identical biochemical and protein profiles and their 16S rRNA gene sequences displayed 99·9% similarity. The G+C content of the DNA of both strains was estimated at 45 mol%. It is concluded that E. minutum and E. tardum are synonyms; E. minutum has priority. An emended description of E. minutum is given.