Publisher Summary Mycorrhizal plants obtain a considerable proportion of their nutrient ions, as well as some potentially toxic elements, by way of the fungal hyphae. Pathbays for solute movement in mycorrhiza are therefore different from those in non-mycorrhizal roots. The structure and physiology of the fungus interacts with that of the root in a poorly understood manner. Identification of sites of localization of elements at the subcellular level, in cell organelles, cytoplasm or cell walls, would help to clarify the process involved in their uptake, transport and deposition or detoxification in mycorrhiza. Electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) are techniques that have recently become available for general use in association with transmission electron microscopy. This chapter reviews EELS and image techniques for subcellular localization of elements in mycorrhiza. EELS and ESI on the transmission electron microscope present a new dimension in electron microscopy.