Immunohistochemistry is concerned with the detection of specific biological substances at the light and electron microscopic levels with antibodies labeled with visible markers, such as horseradish peroxidase and colloidal gold. In particular, the immunohistochemistry of electron microscopy has provided much morphological and biological information. Immunoelectron microscopy can be classified into three methods, i.e., pre-embedding, postembedding, and nonembedding methods, on the basis of the step during which the immunoreaction is applied to the biological specimens. Each method has both advantages and disadvantages, so we should select the method according to the biological purpose. An overview of immunoelectron microscopy is given, and several electron micrographs using immunohistochemical techniques are shown.