During continuing studies on biologically active compounds from clinical isolates of Nocardia species1-4), one antitumor compound called asterobactin (1), was isolated from the mycelial cake of a clinically isolated Nocardia asteroides IFM 0959 strain.Structural elucidation suggested that 1 is a new siderophore group antibiotic (Fig. 1). In this paper, we report the production, isolation, physicochemical properties, structural characteristics and biological activity of the antibiotic.