During the course of screening for inducers of mouse myeloid leukemic cell (M1) differentiation, four active components related to carminomycins were isolated from the cultured broth of an actinomycete identified as Actinomadura roseoviolacea. The isolation and structures of these components are reported. Components A, B, and C were confirmed to be carminomycin II, carminomycin I, and 13-dihydrocarminomycin, respectively. Component D was determined to be N-formyl-13-dihydrocarminomycin (C27H29O11N) through spectral analyses (1H NMR, 13C NMR, FD-MS) and chemical reactions (acid hydrolysis, hydrogenolysis). A non-glycosidic compound E (C20H18O7) was also obtained from the third band, with its structure proposed based on high resolution mass spectroscopy and 1H NMR data. These compounds (A, B, C, and D) induced phagocytic activity and morphological change of M1 cells at 0.1~0.2 pg/ml. Further studies on their biological activities are in progress.