In investigating 0.5- to 5 Μm-thick deformed samples in a 1000 kV high-voltage electron microscope, the formation and structure of crazes were studied in different amorphous polymers (PS, SAN, PVC, and the highly radiation-sensitive polymers PMMA and PC). Different craze types were found and classified. There are some types of “true crazes” with a fibrillar structure or rather a homogeneous structure, which have to be distinguished from only “craze-like deformation zones”. A peculiarity was found in PMMA which produces a craze type different in structure from the well-known fibrillated crazes typical of PS.