A new compound designated as clonoamide was isolated from a culture broth of the fungus Clonostachys sp. BF-0131 by solvent extraction, Diaion HP20 column chromatography, octadecylsilyl column chromatography and preparative HPLC as an inhibitor of sterol O-acyltransferase (SOAT). The structure of clonoamide was elucidated as 2-oxo-9E,11E-tridecandienyl acetamide by various spectral analyses including NMR. The compound inhibited SOAT1 and SOAT2 isozymes with IC50 values of 39 and 110 μm, respectively, in a cell-based assay using SOAT1- and SOAT2-expressing Chinese hamster ovary cells.