The title compound C18H17FO4 was synthesized and recrystallized from an organic solution. The crystal structure of 1-(4-fluorophenyl)-3-(3,4,5-trimethoxyphenyl)2- propen-1-one was determined by X-ray diffraction analysis. The title compound crystallizes in the monoclinic crystal class in the space group P2(1)/c with cell parameters a = 7.6930(6) angstrom, b = 15.2320(11) angstrom, c = 14.1280(12) angstrom, beta = 106.596(3)degrees, Z = 4, and V = 1586.6(2) angstrom(3). The unsaturated keto group is not strictly planar and is in a s-cis conformation.