In the title compound, Bi(2)B(8)O(15), the Bi atom is coordinated to five or six O atoms. The B atoms exhibit two kinds of hybridization, sp(2) and sp(3), seen in the BO(3) triangles and BO(4) tetrahedra, respectively. Three BO(3) triangles are connected to form a B(3)O(6) planar ring. All atoms in the structure are connected together to form an infinite three-dimensional network.