In the title compound, C(22)H(16)O(2), the phenanthrene ring system is essentially planar [maximum deviation = 0.058 (1) Å] and is inclined at an angle of 58.39 (6)° to the phenyl ring. The 1,4-dioxane ring is in a chair conformation. In the crystal, mol-ecules are stacked along the b axis, but no significant hydrogen bonds are observed.