A review of the applications of the scanning electron microscope cathodoluminescent mode is given. Particular attention is devoted to the kind of information that can be obtained by modifying the method in different ways, the problems of spatial resolution and the formation of image contrasts. Results obtained for GaAs, GaP and other optoelectronic materials show the advantages of the local cathodoluminescence method in determining local values of electrophysical parameters in multilayer epitaxial structures, distribution of optically active impurities, etc. These features make the method uniquely useful for the growth of optoelectronic structures with prescribed properties.