The influence of severe plastic deformation induced by ECAP on microstructure modification and aging effect was studied in two modified Al-Mg-Si aluminium alloys. The microstructure of both alloys in different heat treated and deformed state was characterised by X-Rays diffraction and polarised light microscopy. The effect of artificial aging was investigated after ECAP performed on samples in the as extruded condition. The aging effect was followed by hardness and electrical conductivity measurements. At higher aging temperature (170°C) the alloys showed an increasing softening with time due to recovery or/and grain coarsening effect. At the lower aging temperature, the hardness remains almost constant due to enhanced precipitation hardening effect.