Deformation mechanisms in postfractured high-thermal-resistant poly(acrylonitrile-butadiene-styrene) (ABS) were investigated using transmission electron microscopy (TEM) and small-angle X-ray scattering (SAXS). Although crazes were clearly identified by TEM, they were not detectable by SAXS. This was possibly due to a short distance between sample and imaging plate in the SAXS set-up and invisibility of craze fibril scattering from the postfractured samples. A rhomboid-shaped SAXS pattern was obtained from ABS samples with high ductility but with no crazes shown in the TEM micrographs. It is believed that the rhomboid-shaped SAXS pattern was generated from matrix shear yielding. The results show that a combination of TEM and SAXS enable us to distinguish crazing and shear yielding in the postfractured ABS,