Three new compounds, 4'-(4,5-dimethyl-1,3-dioxolan-2-yl)methyl-phenol (1), (3'-hydroxybutan-2'-yl)5-oxopyrrolidine-2-carboxylate (2), and atroviridetide (3), have been isolated from the marine-derived fungus Trichoderma atroviride G 20-12. Their structures were determined on the basis of chemical and spectroscopic methods.