A number of isoechinulin-type metabolites, characterized by a dehydrotryptophan unit, all containing isoprenic and reversed isoprenic chains in the 2- and 5-positions of the indole nucleus, respectively, have been isolated from molds of the genus Aspergillus.1)Their common biosynthetic origin from cyclo-L-alanyl-Ltryptophanyl has been established.2)During a search for bioactive constituents from marine microorganisms,3) we have previously isolated diketopiperazines (2, 3, 4) from a marine-derived Aspergillus sp.4) In a continuing study of the more polar fractions from the same fungus, we have isolated a new metabolite, dihydroxyisoechinulin A (1), and related echinulin (5).5)