The pnictides RE(2)Mn(3)Cu(9)Pn(7) (Pn = P, As) have been prepared by stoichiometric reaction of the elements at 800 degrees C. They are quaternary ordered variants of the hexagonal Zr2Fe12P7-type structure (Pearson symbol hP21, space group P (6) over bar, Z = 1; a = 9.6444(3)-9.5970(7) angstrom, c = 3.9027(1)-3.7761(3) angstrom for RE2Mn3Cu9P7 (RE = La-Nd, Sm, Gd-Dy); a = 9.9376(6)-9.9130(3) angstrom, c = 4.0194(2)-3.9611(1) angstrom for RE2Mn3Cu9As7 (RE = La-Nd)). Of the four possible sites available for the transition metal, the square pyramidal site (CN5) is occupied preferentially by Mn atoms, whereas the three tetrahedral sites (CN4) are occupied by Cu atoms. On proceeding to smaller RE members in the RE(2)Mn(3)Cu(9)Pn(7) series, one of the transition-metal-centered polyhedra (Cu1) tends to become less distorted, while the remaining three (Cu2, Cu3, Mn4) become more distorted. Band structure calculations on La2Mn3Cu9P7 confirm that Mn-P and Cu-P contacts provide the strongest bonding interactions. Electrical resistivity measurements on Ce2Mn3Cu9P7 reveal metallic behavior with transitions at 165 and 18 K, probably of magnetic origin.