Formalin-fixed samples from the demyelinated frontal white matter of an autopsy case of adult-onset MLD were studied by electron microscopy. The intracellular storage materials exhibited the following types of structural patterns: (I) ordinary myelin figures; (II) pleated myelin figures; (III) narrow stacks of lamellar discs which were most likely components of formerly compact "prismatic" inclusions; (IV) paired lamellae, either arranged in loose parallel arrays or scattered about in random directions; (V) piles of parallel lamellae with alternating electron-dense and electron-lucent inter-spaces; and (VI) collections of structures resembling fragments of so-called pentalaminar membranes. Types I to IV have already been described in early-onset as well as late-onset forms of MLD, but types V and VI have not. Postmortem autolysis had possibly altered the structural organization of some cytoplasmic deposits and given rise to the formation of those lamellar patterns which were hitherto not known to occur in MLD.