The mechanical properties and phase morphology of compatibilized blends of acrylonitrile-butadienestyrene (ABS) with a wide range of polyamide materials having different physical and chemical characteristics were explored. The most efficient dispersion of the ABS phase and the best combination of mechanical properties occur within an optimum range of the nylon/ABS viscosity ratio. It is significantly more difficult to disperse the ABS and to generate toughened blends when the polyamide material is difunctional in character, i.e, a fraction of the chains having two amine end-groups. Increasing the inherent ductility of the polyamide leads to improved toughness of these blends.