Two new octahydronaphthalene derivatives, trichodermic acid A ( 1) and trichodermic acid B ( 2), along with a known analog, trichodermic acid ( 3), and a known modified dipeptide, trichodermamide A ( 4), were isolated from the extract of Trichoderma spirale, an endophytic fungus present in the medicinal plant Aquilaria sinensis. The structures of these compounds were established by extensive analysis of their spectroscopic data including 1D- and 2D-NMR and MS data.