Dityromycin is a peptide antibiotic isolated from the culture broth of the soil microorganism, Streptomyces sp. strain No .lPM-~iS~~Fo,"~~n~aSa:::::tfiee~ against Bacillus, Corynebacterium, and Clostridium. to be composed of N-MeVal, Pro, Val, Phenylglycine. CH NH2. amino acid containing diphenylether moiety. The pepti .I? e N.N-Me2Thr and di-asequence except one labile amino acid residue was determined by partial hydrolysis, chemical cleavage, and the Edman degradation. The unknown amino acid was finally deduced to be the dehydroamino acid containing epoxide. resulting in an elucidation of whole structure of the antibiotic.