A novel actinomycete, strain N1286(T), isolated from a lung transplant patient with a pulmonary infection, was provisionally assigned to the genus Nocardia. The strain had chemotaxonomic and morphological properties typical of members of the genus Nocardia and formed a distinct phyletic line in the Nocardia 16S rRNA gene tree. Isolate N1286(T) was most closely related to Nocardia farcinica DSM 43665(T) (99.8% gene sequence similarity) but could be distinguished from the latter by the low level of DNA-DNA relatedness. These strains were also distinguishable on the basis of a broad range of phenotypic properties. It is concluded that strain N1286(T) represents a novel species of the genus Nocardia for which the name Nocardia kroppenstedtii sp. nov. is proposed. The type strain is N1286(T) ( = DSM 45810(T) = NCTC 13617(T)).