A novel rigid poly(vinyl chloride) (PVC)/acrylonitrile-styrene-acrylate (ASA) copolymer blend with good ultraviolet (UV) irradiation resistance and toughness was reported. ASA with good weatherability and toughness was mixed with PVC by conical twin-screw extruder to improve the UV irradiation resistance and toughness of PVC. The blends were characterized using Fourier-transform infrared spectra, dynamic mechanical analysis, and scanning electron microscope. Notch Charpy impact test was used to characterize the UV radiation induced changes in toughness. The results showed that ASA was able to toughen PVC with simultaneously improving heat resistance, thermal stabilization, and protecting PVC from irradiation photochemical degradation. (c) 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2143-2151, 2013