During the course of a study of blocked mutants or variant strains derived from Streptomyces violaceus A262 a known producer of diglycosidic β-rhodomycins, we have isolated several which produce new anthracyclines. One of these, strain SC-7 was found to produce α-citromycinone glycosides as minor components from which yellamycins were obtained by means of controlled hydrolysis. This strain was deposited as FERM P-8720 in Fermentation Research Institute, Agency of Industrial Science and Technology. In this paper, we describe the isolation, structural determination and biological activity of yellamycins A, B and C. Yellamycins are new α-citromycinone glycosides which possess L-rhodosamine at the C-7 and/or C-10 position.