In the course of our screening for new antibiotic, new members of benz[a]anthraquinone antibiotics (I and II), which showed antibacterial activity against Gram-positive bacteria were isolated from a culture broth of Streptomyces tsusimaensis MI310-38F7. This strain produced nonactin and a minor yellow compound (III) which was identical with X-14881 E1}. This report describes the isolation, characterization and structure determination of these compounds, named 6-deoxy-8-0-methylrabelomycin (I) and 8-0-methylrabelomycin (II).