Hyaline necrosis of epidermal cells either single or in clumps represents apparently the primary change in the measles eruption. Lesions occur, however, very soon in the corium and could be demonstrated twelve hours after the onset of the eruption. The early lesions (twelve to thirty-six hours) in the epidermis show usually different stages in a single slide examined. They are described as minute vesicles and pustules; in older lesions the pustules have dried up forming thickened plaques in and beneath cornified layer. Parakeratotic cells with intranuclear bodies first described by TORRES & TEIXIERA (1932 b) while inconstant are regarded as a pathognomonic change in measles eruption. Edema of the papillary layer and perivascular infiltrations in the reticular layer by large mononuclears some of them containing small irregular deeply stained granules (MALLORY-MEDLAR-LIPSCHÜTZ' cells) are well known changes largely referred in the literature. Evidence is here submitted in support of the opinion that such cells correspond to macrophages with keratohyaline granules phagocited as a consequence of changes in cornification determined by the virus itself. Microscopic examination is necessary for the demonstration of the minute vesicles and pustules which are such an important detail in the histology of the measles eruption as it establishes connections between measles usually considered in the group of exanthematous diseases with chicken-pox, zoster, small-pox and alastrim (pustulous diseases). Epidermal changes are no more found seventy-two hours after the onset of the eruption while well-defined mantles of cells about the vessels and a moderate proliferation of fibrocytes is noticed in the corium.