Abstract Recently the minor metabolises, PC-M5′and PC-M6, were isolated along with the tremorgenic mycotoxins, penitrems A–F, from the mycelium of Pencillium crustosum, which was found contaminating bread intended for school lunches in Tokyo city. Two new indoloditerpenes, PC-M4 and PC-M5, were also isolated from the above fungus. The structures of these two compounds were determined on the basis of spectroscopic investigations. PC-M4 has the same carbon number as the penitrems but a different cyclic ring system. PC-M5 might be a biosynthetic precursor of penitrems and PC-M4 as may also PC-M5′ and PC-M6.