Sir:Wehave previously reported on baumycins Al, A2, Bl and B21}, which are daunorubicin analogues having unique acetal moieties at 4' position. In a continuing search for new antitumor antibiotics, extremely potent anthracyclines, which attach a new type of 4'-O-substituent, were isolated from a carminomycin-producing strain designated MG463-yF4, and named barminomycins I (1)2) and II (2). The culture broth of this strain exhibited a significant activity against L1210 leukemia and B16 melanoma cells in mice. In this broth five components of anthracycline-glycosides were detected, but three of them, carminomycins I, II and III3), were less potent than a mixture of the anthracyclines in the broth. Accordingly we attempted to isolate two others. In this communication, the production, isolation and characterizationof anthracyclines 1 and 2 are reported.