Structure-property relationships in commercial 1560 (Al-6.0 wt.% Mg-0.6 wt.% Mn) aluminium alloy subjected to equal-channel angular extrusion (ECAE) and subsequent annealing have been analyzed. The features of the submicrocrystalline (SMC) deformation structure obtained by ECAE and its transformation into submicro- and microcrystalline grain structures upon annealing were studied by optical and transmission electron microscopy, and X-ray diffraction. The nature of recrystallization and phase transformation processes upon annealing is discussed. The alloy mechanical behaviour has been characterized by static tension and bending experiments at room temperature. The effects of ECAE and annealing on serrated flow, strength, hardness, ductility and crack resistance of the alloy are demonstrated. In contrast to the usually observed behaviour of ECAE-processed Al alloys, ductility and crack resistance decreased with transformation the SMC structure upon low-temperature annealing, which is attributed to the formation of β precipitates during annealing treatment.