Over the last decade, our knowledge of the parasites causing malaria has been transformed by molecular biology. We now have an exten- sive body of data concerning many of the proteins and the genes encoding them, but much less is understood about their cellular functions. The localization of parasite macromolecules to identified structures within or in the vicinity of the organism can provide valuable clues about their biological roles, and, because of the small dimensions of the organism, immunoelectron microscopy (IEM) is essential for this purpose. It is therefore now almost routine for immunoelectron micro- scopic localization to be part of the formal characterization of a newly discovered malaria antigen. However, the methods required for IEM are themselves not routine, and relatively few laboratories have carried out this type of work.