Six reference strains of the genus Brevibacterium as well as fifteen clinical isolates tentatively assigned to the genus using conventional biochemical methods, were the subject of chemotaxonomic and DNA similarity studies. Five of these clinical isolates were assigned either to the genera Aureobacterium, Mycobacterium, Gordona or to Rhodococcus on the basis of their DNA mol% G+C, mycolic acid, amino-acid, sugar and menaquinone contents. Among the ten remaining strains, six were not brevibacteria and only four conformed to the description of the genus Brevibacterium sensu stricto. These strains showed low values of DNA relatedness with Brevibacterium epidermidis ATCC 35514T and Brevibacterium linens ATCC 9174, and could only be described as Brevibacterium spp. The results indicate that studies of chemical markers are essential for the correct identification of brevibacteria.