The technique of reflection electron microscopy has been applied to the imaging of GaAs/Alx,Ga1−xAs multilayer materials. The image contrast of the multilayer materials is shown to result mainly from the composition variation across the structures. We demonstrated that, by using surface resonance effects, an GaAs/AlxGa1−xAs epitaxial layer with 1·0% Al can be identified, and a multiplequantum-well structure with periodicity down to 20 Å can be imaged.