A new meroterpenoid asperdemin (1) and two known compounds, viz., diorcinol (2) and viridicatol (3), were isolated from the marine fungus Aspergillus versicolor. The structures of these compounds were established by NMR spectroscopy and highresolution mass spectrometry. The absolute stereochemistry of 1 was determined by modified Mosher's method. The antimicrobial activity of the total extract from A. versicolor was attributed to diorcinol (2). Asperdemin exhibits weak cytostatic and membranolytic activities in developing embryos of the sea urchin Strongylocentrotus nudus.