In the title mol-ecule, C21H18O4, the C=C bond of the central enone group adopts a trans conformation. The dihedral angle formed by the naphthalene ring system and the benzene ring is 2.97 (11)°. The hy-droxy group is involved in an intra-molecular O-H⋯O hydrogen bond. In the crystal, weak C-H⋯O hydrogen bonds link the mol-ecules into chains along [001].