In 30 patients suffering from different clinical forms of lupus erythematosus (LE), previously chronic discoid lesions of different activity were investigated by electron microscopy. In early stages we found increased infoldings and reduplications of the basement membrane (BM) along the distinctly elongated basal cell projections and reticulated deposits of BM-like granular to fibrillar material corresponding to immune complexes. In necrobiotic stages these alterations are more distinct and accompanied by necrobiosis and inflammation leading over into the atrophic stage. Between chronic and systemic forms there are transitions and quantitative differences dependent on the duration and activity of the disease. Because of the temporal preference of the subepidermal region in early stages we consider the corium as the site of primary alteration in the LE.