Five aerobic actinomycete strains isolated from patients in Japan were assigned provisionally to the genus Nocardia based on morphological and physiological characteristics. The five strains, IFM 10481, IFM 0668, IFM 0901, IFM 0583 and IFM 0342, were not classified into any Nocardia species reported as infectious agents in Japan. Therefore, they were studied further to determine their specific taxonomic positions. Detailed chemotaxonomic and physiologic characterization and 16S rDNA sequence data of the five strains showed that they belonged to respective species of Nocardia carnea, N. elegans, N. paucivorans, N. puris and N. takedensis. This is the first isolation report of these five Nocardia species from patients in Japan.