In the title compound, C(16)H(13)NO(4), the indole system is essentially planar, whereas the dioxane ring adopts a twist conformation. The mol-ecules are linked into chains by -O- H⋯O=C- hydrogen bonds and these chains are linked into rods by means of N-H⋯O hydrogen bonds. Exept for weak C-H⋯O inter-actions between the rods, no other inter-molecular contacts of inter-est are present.