Thin films of &agr;Rh2As were grown on top of GaAs (001) in a molecular‐beam epitaxy system by codeposition of rhodium and arsenic from separate sources. &agr;Rh2As is a good metal with a resistivity equal to 20 &mgr;&OHgr; cm, suitable for electronic applications. The holes, the only type of carriers, have a concentration equal to 2.5×1022cm−3, i.e., a value of the same order of magnitude as that of the best silicides. However, in spite of several features common to &agr;Rh2As and GaAs (symmetry, almost equivalent unit‐cell constant, and fcc As sublattices), the epitaxial arrangement [100](011)&agr;Rh2As//[110](001)GaAs mainly prevails instead of the expected simple unrotated relationship [100](001)&agr;Rh2As//[100](001)GaAs. This points out that the achievement of the minimum lattice mismatch is not always the driving force for the epitaxy. In agreement with the ternary phase diagram Rh‐Ga‐As, the (polycrystalline &agr;Rh2As)/GaAs system interacts above 400 °C and leads to the formation of the binary compounds RhGa and RhAs2.