Two actinomycete strains, 0351M-12(T) and 0385M-1(T), were isolated from sediment samples collected from Yilan County and Dali City in Taiwan, respectively. The two isolates displayed characteristics which were similar to those of the genus Herbidospora. They both produced branched and unfragmented substrate mycelia, and aerial hyphae were not produced on Bennett's, glucose-asparagine, Hickey-Tresner, sucrose-nitrate, yeast extract-malt extract, or inorganic salts-starch agars. Short spore-chains were borne on the tips of sporophores arising from the substrate mycelia on oatmeal and oatmeal-nitrate agars. The spore chains contained 10-20 non-motile, smooth-surfaced, oval spores. Galactose, glucose, mannose and madurose were the whole-cell sugars in both strains and meso-diaminopimelic acid was present in their peptidoglycans. The phospholipid pattern was PIV. The predominant menaquinone was MK-10(H(4)) in both strains. Mycolic acids were not detected. Major cellular fatty acids were iso-C(16 : 0) and 10-methyl C(17 : 0). The DNA G+C contents of the two new isolates were 70.6 mol% (0351M-12(T)) and 70.7 mol% (0385M-1(T)), respectively. The relatedness between the isolates and Herbidospora cretacea NBRC 15474(T) was 40.7-48.5 %. The value of DNA-DNA hybridization between strain 0351M-12(T) and strain 0385M-1(T) was 53.6-54.9 %. These two isolates could also be distinguished from each other and from H. cretacea NBRC 15474(T) by differences in several phenotypic characteristics. We therefore propose the names Herbidospora yilanensis sp. nov. and Herbidospora daliensis sp. nov. for these novel bacteria, with strains 0351M-12(T) (=FIRDI 003(T) =BCRC 16875(T) =LMG 24337(T)) and 0385M-1(T) (=FIRDI 004(T) =BCRC 16876(T) =LMG 24336(T)) as the type strains, respectively.