The ultrastructural changes in seven cases of lichen sclerosus et atrophicus are described. An interesting epidermal alteration was the presence of collagen fibrils in the intercellular space; furthermore, the basal cells were altered by condensation and homogenization of the tonofibrils. The basement membrane was not uniform and often multilayered. The anchoring fibrils were numerous. In the cutis intertwining strands of fine filaments, bundles of immature collagen and normal collagen could be found. In lichen sclerosus et atrophicus the dermo-epidermal interrelationship is disturbed.