A new antitumor antibiotic, fredericamycin A (FCRC-A48, NSC-305263), has been isolated from a strain of Streptomyces griseus (FCRC-48). Based on its unique ultraviolet-visible spectrum, infrared spectrum, proton and carbon-13 nuclear magnetic resonance spectra and mass spectra, it is judged to be a novel acid-base indicator type of compound. Its production, isolation and physicochemical properties are discussed. The isolation, ultraviolet-visible spectrum and some biological properties of two minor components, fredericamycin B and fredericamycin C, are also described.