The asymmetric unit of the title compound, [Tb(2)(C(3)H(7)NO(2))(4)(H(2)O)(8)](ClO(4))(6), contains a dinuclear cation and six perchlorate anions, one of which is disordered. In the cation, the four l-alanine mol-ecules are present in their zwitterionic form and bridge two Tb(3+) ions through their carboxyl-ate O atoms. Each Tb atom is also coordinated by four water mol-ecules in a square-anti-prismatic geometry. In the crystal structure, the cations and anions are held together via inter-molecular O-H⋯O and N-H⋯O hydrogen bonds.