Sir: We have recently discovered two new antibiotics, designated LL-E19020α (1) and LL-E19020β (2), which are highly modified versions of the aurodox family. The LL-E19020 antibiotics have an exceptionally narrow antimicrobial spectrum against human pathogens, showing meaningful activity versus Streptococcus species and certain anaerobes (MIC 0.1-1 μg/ml). These compounds are highly effective as growth promoting agents in animals, producing superior performance in chicks in comparison trials with bacitracin and virginiamycin. The details of the biological activity of these compounds, the taxonomy and fermentation of the producing organism, and the structure elucidation will be the subjects of separate reports.