Ankinomycin, a new member of the pluramycin antibiotics, which is shown here to be deangolosaminylhedamycin, has been isolated together with hedamycin from the culture broth of Streptomyces sp. SF2587 (FERM-P 9831). The strain was isolated from a soil sample collected in Takatsuki-city, Osaka Prefecture, Japan. The antibiotic is active against Gram-positive bacteria, and exhibits potent antitumor activity against P388 leukemia in mice. These activities are superior to those of hedamycin. In this communication, the isolation, characterization and structural elucidation of the antibiotic are reported.