The amorphization of Al-20 mol % Cr alloys were investigated when different starting powders were mechanically ground using a vibration-mill. Mechanical grinding (MG) of two types of starting powders were examined : (1) single delta (Al-20 mol % Cr) phase powders and (2) a mixture of gamma (Al-15 mol % Cr) and epsilon (Al-30 mol % Cr) phases powders. Amorphous Al-Cr alloys could not be obtained by MG of single intermetallic compound (delta phase) as the starting powders. But in the case of MG using the mixture of intermetallic com pounds (gamma and epsilon phases), some parts of the MG powders changed phase into an amorphous phase with a Cr content of about 30 mol % at the initial stage of the milling. On further milling, the formed amorphous phase reacted with residual crystalline gamma phase (Al-15 mol % Cr) to produce an amorphous phase with a Cr content of 20 mol %. The former amorphous phase crystallized into the delta and epsilon phases, and the latter crystallized into an equilibrium delta phase by subsequent heat treatment.