New antifungal antibiotics, benanomicins A and B, possessing a benzo[tf]naphthacene quinone skeleton have been found in the culture filtrate of Actinomycete sp. MH193-16F4. This strain is related to Actinomadura, but cannot be identified. Benanomicins A and B are active against fungi and some Gram-positive bacteria. In this communication, we report the isolation, characterization and structural elucidation of the antibiotics.