Previously, we have reported the isolation and structure determination of six novel anthracycline antitumor antibiotics from the bohemic acid complex. We now report the isolation and structure determination of schaunardimycin. During large scale fermentation for marcellomycin production, a new component (schaunardimycin) was found which complicated chromatography using CH₂Cl₂-MeOH-NH₃ based systems on silica gel. Partial resolution was improved by substituting CHCl₃ for toluene-MeOH, and pure schaunardimycin was obtained from the second major fraction via Sephadex LH-20 chromatography. The structure was determined by nmr studies: cmr chemical shifts were very similar to those of musettamycin except for carbon atoms in the vicinity of the amino sugar nitrogen, with strong upfield shifts for C-3' (61.8 ppm to 54.8 ppm) and N-methyl groups (42.7 ppm to 33.2 ppm), and lesser downfield shifts for C-2' (29.2 ppm to 31.8 ppm) and C-4' (73.6 ppm to 77.7 ppm); the pmr spectrum was similar to musettamycin except the N-methyl signal integrated for three protons and shifted downfield from 2.22 to 2.35. Biologically, schaunardimycin appears to have about a tenth of the potency of musettamycin and around one-twentieth that of marcellomycin.