MgAuGa is the first ternary representative of the Mg–Au–Ga system. It adopts the Fe2P structure type (Pearson symbol hP9) and closely resembles hexagonal Mg2Ga through a direct group–subgroup relationship. MgAu2Ga also crystallizes hexagonally and is isotypic with Na3As. It adopts the structure of another binary compound, viz. Mg3Au (hP8), but shows an unexpected distribution of Mg, Au, and Ga among the atomic positions of the asymmetric unit compared to Mg3Au.