Four new azaphilones of angular type, named chaetociridins A, B, C and D, were isolated from the culture of Chaetomium globosum var. flavo-viridae. The absolute configuration of chaetoviridin A was established on the basis of the spectral data and chemical reactions. The structures of chaetoviridins B, C and D were suggested by the spectral data. The result of a biosynthetic study of chaetoviridin B from sodium [1, 2-¹³C₂]acetate gave support to the angular structure.