Morphologic diagnosis of many neurometabolic storage diseases can be achieved by electron microscopic examination of skin biopsies and/or peripheral lymphocytes. Pathognomonic inclusions of specific shape allow accurate diagnosis in ceroid neuronal lipofuscinosis, generalized glycogenosis, Tangier disease, metachromatic and globoid leukodystrophy, and sometimes in adrenoleukodystrophy. Vacuolation of cells and membranous cytoplasmic and zebra bodies, while not specific for individual diseases, still indicate the presence of one of a limited group of disorders. This method is especially useful in those inborn errors of metabolism for which biochemical tests are not available.