An extensive taxonomic investigation identified strain SK&F-AAJ-271 as a new species, designated Actinomadura parvosata. Fermentations of this organism produce a complex of acidic, lipophilic glycopeptide antibiotics, the parvodicins. Structures for seven of the isolated components were derived from a combination of mass spectral, high-field NMR and chemical techniques. The O-acetyl functionality present in two of the isolated components is a structural feature unique among the known members of this class of antibiotics. The parvodicins are active in vitro against a range of Gram-positive bacteria. The most active parvodicin, C1, produces high serum levels in vivo and has the potential for a long duration of action.