[en] The XRMS experiment on the Gd₅Ge₄ system has shown that, below the Neel temperature, T_N = 127 K, the magnetic unit cells is the same as the chemical unit cell. From azimuth scans and the Q dependence of the magnetic scattering, all three Gd sites in the structure were determined to be in the same magnetic space group Pnma. The magnetic moments are aligned along the c-axis and the c-components of the magnetic moments at the three different sites are equal. The ferromagnetic slabs are stacked antiferromagnetically along the b-direction. They found an unusual order parameter curve in Gd₅Ge₄. A spin-reorientation transition is a possibility in Gd₅Ge₄, which is similar to the Tb₅Ge₄ case. Tb₅Ge₄ possesses the same Sm₅Ge₄-type crystallographic structure and the same magnetic space group as Gd₅Ge₄ does. The difference in magnetic structure is that Tb₅Ge₄ has a canted one but Gd₅Ge₄ has nearly a collinear one in the low temperature antiferromagnetic phase. The competition between the magneto-crystalline anisotropy and the nearest-neighbor magnetic exchange interactions may allow a 3-dimensional canted antiferromagnetic structure in Tb₅Ge₄. The spin-reorientation transition in both Gd₅Ge₄ and Tb₅Ge₄ may arise from the competition between the magnetic anisotropy from the spin-orbit coupling of the conduction electrons and the dipolar interactions anisotropy