In the structure of the title compound, C(28)H(16)O(6)·H(2)O [systematic name 3,11-bis(4-hydroxyphenyl)-4,12-dioxapentacyclo[8.6.1.1(2,5).0(13,17).0(9,18)]octadeca-1(16),2,5(18),6,8,10,13(17),14-octaene-7,15-diol monohydrate], the hopeahainol C mol-ecule lies about an inversion center with the solvent water mol-ecule located on a crystallographic twofold axis. Hopeahainol C is an oligostillbenoid compound and was isolated from the bark of Shorea roxburghii G. Don. The five central fused rings are essentially planar with an r.m.s. deviation of 0.0173 (3) Å. The 4-hy-droxy-phenyl ring is twisted with respect to this plane, with the dihedral angle between the phenyl ring and the fused-ring system being 41.70 (10)°. The crystal features inter-molecular O-H⋯O hydrogen bonds. These inter-actions link the hopeahainol C mol-ecules into chains along the b axis. Water mol-ecules are located inter-stitially between the hopeahainol C mol-ecules linked by O(water)-H⋯O(hy-droxy) and O(hy-droxy)-H⋯O(water) hydrogen bonds. π-π inter-actions are also observed with centroid-centroid distances of 3.6056 (17) and 3.5622 (17) Å. Short O⋯O contacts [2.703 (2)-2.720 (3) Å] are also present in the crystal.