Ternary aluminium alloy Al-3Mg-0.2Sc was subjected to equal-channel angular pressing (ECAP) at room temperature to refine its original coarse grain size. For this purpose the ECAP die was used which had a 90° angle between the die channels. By application of this method an ultrafine-grained microstructure was achieved with the grain size ~ 0.3mm after 8 ECAP passes by route BC. Subsequent compression constant stress creep tests were conducted at 473 K and in the applied stress range of 16–40 MPa. It was found, that resulting microstructure of this alloy leads to a decrease of minimum creep rate by an order of magnitude in comparison with creep behaviour of an ultrafine – grained ECAP pure aluminium. Further, the creep behaviour of Al-3Mg-0.2Sc alloy at lower stresses indicates a possible occurrence of the threshold stress for creep.