This paper describes grain refinement of an Al–3%Mg–0.2%Sc alloy using the equal-channel angular pressing (ECAP) technique at room temperature. It is shown that a grain size of 0.2μm is obtained with this technique. The paper also presents the results of tensile tests for the fine-grained Al–3%Mg–0.2%Sc alloy over a wide range of strain rates. Elongations of more than 1000% are attained at a temperature of 673 K in a high strain rate range of more than 10⁻² s⁻¹. Transmission electron microscopy and scanning ion microscopy are employed for microstructural observations before and after tensile testing. The results are compared with those of a cold-rolled Al–3%Mg–0.2%Sc alloy. It is demonstrated that grain refinement using the ECAP technique is useful for the production of Al alloys exhibiting high strain rate superplasticity.