It is shown that a uniform ultrafine-grained structure in alloy 6061 can be formed already after four cycles of treatment by equal-channel angular pressing in parallel channels (ECAP-PC). Along with grain refinement, in the process of an ECAP-PC treatment there occurs in the alloy a dynamic strain aging, which results in the formation of nanodimensional particles of a strengthening phase Mg₂Si. It has been established that the alloy in the UFG state demonstrates a considerably higher level of strength and better plasticity in comparison with the material after a standard strengthening treatment.