Maleic anhydride (MAR) functionalized acrylate-styrene-acrylonitrile (ASA) copolymers (F-ASA) were prepared via an emulsion polymerization process. The F-ASA particles were used to toughen Polyamide-6 (PA-6). Molau tests showed the compatibilization reactions between PA-6 and F-ASA. The notched impact strength of PA-6 was effectively improved by the use of F-ASA. At a rubber content of 20% by weight in PA-6/F-ASA blends, it was found that the impact strength increased with the MAR content. When the MAR content was 8% in F-ASA, the impact strength was 1008 J/m. The influence of rubber content on the properties of PA-6/F-ASA8 blends was investigated. The results showed that brittle-ductile transition took place when the rubber content was 20%. Moreover, increasing the MAH content of the blends reduced the brittle-ductile temperature of the FASA/PA-6 blends from 50 degrees C to about 0 degrees C. Scanning electron microscopy (SEM) results showed that cavitation of rubber particles and shear yielding of the PA-6 matrix were the major toughening mechanisms.