Together with arugosins A (3), B (4), and C (5), a novel compound related to the arugosins, designated arugosin E (l), was isolated from the mycelial extract of Aspergillus silvaticus. A new compound designated cycloisoemericellin (2) was also isolated along with arugosins A (3) and B (4) from the mycelial extract of Emericella striata. The structures of compounds (1) and (2) were determined on the basis of spectroscopic investigation and chemical correlation with the known compounds (3), (4), and (6). An X-ray crystal analysis of arugosin E (1) was carried out.