The marine fungus Paecilomyces sp., derived from the marine sponge collected along Tinggi Island, Malaysia, was cultivated and incubated for 7 days at 30C. The liquid cultures were then extracted, and the crude extract was investigated for its antimicrobial activity. Purification of the crude extract resulted in the isolation of the new (3R*,5E,7E,9R*,11E,13Z)-1-((3aS*,6aR*)-2-amino-5-oxo-3a,5,6,6a-tetrahydrofuro [3,2-b]furan-3-yl)-3,7,9,11-tetramethylheptadeca-5,7,11,13-tetraene-1,2-dione (1) and four known metabolites, stigmasterol (2), cholesteryl linoleate (3), linoleic acid (4), and 2,5-furandimethanol (5). The structures of the components were elucidated by spectroscopic methods. The antimicrobial activities of all the isolated compounds were evaluated against a panel of bacteria and fungi.