Chlorinated polyethylene (CPE) is a commonly used impact modifier of poly(vinyl chloride) (PVC). The major goal of this research was to understand the fundamental morphological aspects of PVC/CPE blends. Scanning electron microscopy (SEM) was used to image the surface structure of these blends, and both transmission electron microscopy (TEM) and scanning-transmission electron microscopy (S-TEM) were used to image the morphological boundaries of the blends. TEM imaging distinguishes the boundaries between PVC and CPE more clearly or better than does S-TEM, but it is time-consuming. However, some CPE particles are not observed in TEM because of inefficient staining. S-TEM imaging is much faster and does not depend on staining for the imaging of the CPE phase.