The crystal structure of the new quaternary compound Na(8)sCu(4)Nb(2)S(21) consists of infinite double chains of corner-sharing CuS4 tetrahedra. A terminal atom of a S-5(2-) anion, the two terminal atoms of the S-3(2-) Unit, and S2-anions are at the corners of the CuS4 polyhedra. The connection of the CuS4 tetrahedra leads to the formation of two different Cu-S heterorings. The NbS4 and CuS4 tetrahedra share common edges. The double chains are separated by Na+ cations.