The authors investigated three cases of IgA linear dermatosis by immunoelectron microscopy. In two of the cases there were additionally some IgG deposits in the basement membrane zone. The arrangement of the IgA deposits was found to vary. In two cases it was of the dermal and the lamina lucida type at the same time, and in one case it was so close to basal cell membranes as to leave an electronlucent space on the side facing the basal lamina. In the third case, the arrangement (only IgG and complement were studied) was exclusively of the dermal type. In one of the cases the deposits had first, i.e., 1 1/2 years earlier, been confined to the lamina lucida, whereas now they were also seen below the basal lamina, although the clinical condition of the patient had remained unchanged. It would seem that the localization of IgA deposits in the basement membrane zone may vary, depending on the evolution of the disease.