In the course of our screening program for anticancer agents from natural sources, five new angucyclines, JBIR-90 (1), -116 (2), -91 (3), -92 (4) and -93 (5), were isolated from the fermentation broth of Streptomyces sp. RI33. The structures of 1-5 were elucidated on the basis of 1D and 2D NMR spectroscopy and MS analyses. Compounds 2-4 showed cytotoxic activities against malignant pleural mesothelioma cells at IC(50) values of 20-50 μM.