A nanostructured Al-1 % Si alloy has been produced using extremely high purity Al (99.9996 %) containing 1 % Si present in the form of dispersed particles. The Si particles stabilize the structure and prevent recrystallization during cold rolling, which has been carried out to a very high strain . The microstructure, strength, and ductility are characterized and the observations are analyzed and discussed focusing on effects of matrix purity and particles in a fine dispersion.