The quaternary rare earth nickel aluminum germanide series RE NiAl 4 Ge 2 ( RE = Y, Sm, Gd–Tm, Lu) has been extended by several members. The compounds were synthesized from the elements by arc-melting, and single crystals of YNiAl 4 Ge 2 , GdNiAl 4 Ge 2 , and LuNiAl 4 Ge 2 were grown from an aluminum flux. All members crystallize isostructurally in the rhombohedral SmNiAl 4 Ge 2 -type structure ( R 3̅ m , Z = 3). The compounds can be described as a stacking of RE δ+ and [NiAl 4 Ge 2 ] δ− slabs with an ABC stacking sequence, or alternatively as stacking of CsCl and CdI 2 building blocks. The results of the magnetic measurements indicate that all rare earth atoms are in a trivalent oxidation state. Of the RE NiAl 4 Ge 2 series, the members with RE = Sm, Gd–Dy exhibit antiferromagnetic ordering with a maximum Néel temperature of T N = 16.4(1) K observed for GdNiAl 4 Ge 2 . 27 Al NMR spectroscopic investigations yielded spectra with two distinct signals, in line with the crystal structure, however, significantly different resonance frequencies of δ iso ms (YNiAl 4 Ge 2 ) = 77(1) and 482(1) ppm as well as δ iso ms (LuNiAl 4 Ge 2 ) = 90(1) and 467(1) ppm were observed. These indicate significantly different s -electron densities at the two crystallographically different Al atoms, in line with the results from DFT calculations. The Bader charge analysis confirms that the present compounds must be considered as germanides, as expected from the relative electronegativities of the constituent elements, while the low charges on Al and Y indicate significant covalent bonding.