In the title compound, C(20)H(17)NO(4), the double bond of the acrylonitrile group separating the 1-benzofuran moiety from the 3,4,5-trimeth-oxy-phenyl ring has Z geometry. The 1-benzofuran groups are π-π stacked with inversion-related counterparts such that the furan ring centroid-centroid distance is 3.804 (5) Å. The dihedral angle between the planes of the trimeth-oxy-phenyl ring and the acrylonitrile group is 24.2 (2)°.