By 16S rDNA sequence analysis, two strains identified previously as members of the genus Nocardioides, namely 'Nocardioides fulvus' IFO 14399 and Nocardioides sp. ATCC 39419, were found to form lines of descent distinct from the genus Nocardioides, Therefore, the two strains were studied taxonomically in detail by phenotypic, particularly chemotaxonomic, characterization, and by phylogenetic analysis including other related taxa, The genomic DNA G+C contents of 'N, fulvus' IFO 14399 and Nocardioides sp, ATCC 39419 are 70 and 68 mol%, respectively. The two strains contain LL-diaminopimelic acid as the diamino acid in their peptidoglycan, together with L-alanine at position 1 of the peptide subunit. The predominant menaquinone found in the two strains is MK-9(H-4). The major cellular fatty acid found in the two strains is anteiso-C-15:0, which is a minor component of members of the genus Nocardioides. The diagnostic polar lipid of the two strains is phosphatidylcholine. A phylogenetic tree was constructed which showed that the two strains form evolutionary lineages distinct from other LL-diaminopimelic-acid-containing taxa such as, for example, the genus Nocardioides. On the basis of our data, a new genus, Kribbella gen. nov., and two new species, Kribbella flavida gen, nov., sp. nov. and Kribbellla sandramycini gen. nov., sp. nov., are proposed. It is also proposed that the new genus be included in the family Nocardioidaceae.