Structure parameters and magnetic properties of ternary ErFe 7 Al 5 and YFe 7 Al 5 intermetallics have been determined by X-ray and neutron diffraction. The compounds crystallize in the ThMn 1 2 -type structure of space group I4/mmm with 2a, 8f and 8i sites occupied by the rare earths (R), iron and aluminium, respectively, and remaining Fe and Al on 8j. Lattice constants and interatomic distances are discussed in the context with results of previously investigated R(Fe x Al 1 - x ) 1 2 compounds of lower iron concentrations. Around 320 K, ErFe 7 Al 5 undergoes a magnetic phase transition into a ferrimagnetically ordered state with antiparallel orientations of Er and Fe(8f) spins within the tetragonal basis plane. The moment values are 8.4(2) μ B and 2.9(3) μ B at 4.2 K per Er- and Fe-ion, respectively. In YFe 7 Al 5 , however, no long range magnetic order is observed.