Novel antibacterial antibiotics napyradiomycins A, B1, B2, B3, C1 and C2 have been isolated from the culture broth of Chainia rubra MG802-AF1. In this paper, taxonomy of the producer, and production, isolation, physico-chemical properties and biological activities of napyradiomycins are reported. They contain the naphtopyran chromophore and halogens, and inhibit the growth of Gram-positive bacteria including drug-resistant strains.