The title compound, C(21)H(30)O(6), a natural ent-kaurane diterpenoid, was obtained from the medicinal plant Isodon serra. The five rings in the mol-ecule exhibit the expected cis and trans junctions. The three six-membered rings adopt chair, twist-boat and boat conformations, while two five-membered rings adopt envelope conformations. There are two mol-ecules in the asymmetric unit, related by a non-crystallographic twofold screw axis; the main difference is in the different degrees of distortion of ring B. In the crystal, the mol-ecules are linked by inter-molecular O-H⋯O hydrogen bonds, forming chains along the b axis.