Chemotaxonomic and 16S rRNA gene sequence analyses of four bacterial strains isolated from clinical material clearly demonstrated that these bacteria belong to the genus Nocardia. DNA-DNA hybridization data as well as the physiological characteristics of the isolates indicated that they are closely related and belong to a single species that differs from previously described members of the genus. The name Nocardia abscessus sp. nov. is proposed for these organisms represented by strain IMMIB D-1592T (= DSM 44432T). Strain IMMIB D-1592T exhibits 56.8 and 60.0% DNA-DNA relatedness to Nocardia asteroides ATCC 19247T and Nocardia paucivorans DSM 44386T, respectively.