Supersaturated Al-4.8Zn-1.2Mg-0.14Zr and Al-5.7Zn-1.9Mg-0.35Cu (wt.%) alloys were processed by Equal-Channel Angular Pressing (ECAP) at 200 degrees C. The crystallite size distribution and the characteristic parameters of the dislocation structure of both Al matrix and precipitates were determined by X-ray diffraction line profile analysis, which has been complemented by transmission electron microscopy (TEM) observations. The results show that severe plastic deformation promotes the precipitation process and consequently has a strong influence on the strength of these alloys.