natural weathering of acrylonitrile-butadiene-styrene (abs) was performed in lisbon during 4 months in order to evaluate its stability to uv radiation. surface characterization of photodegraded abs samples was investigated by infrared spectroscopy with attenuated total reflectance accessory (ftir-atr) and the decrease of polybutadiene (pb) component was used as an indicator of the degradation degree. a correlation between chemical modifications on surface and mechanical properties loss was made. infrared spectroscopy coupled to microscope was used to study degradation along sample thickness. it was noticed that for this sample a drastic decrease of pb occurred only at the surface, which indicate that the decrease of elongation capability of abs during degradation process is also due to the cracks formation and its propagation along the thickness.