This study is concerned with the intercellular substances in circumscribed scleroderma. An intimate puzzle-like contact of irregularly surfaced collagen fibers with elastic fibers and cells inhibits the movability of the tissue elements, which may explain the clinical hardening. Confirming earlier investigations the mean thickness of the collagen fibrils is smaller than in normal skin. The histograms may exhibit one or two maxima, the position of which is not fixed. Similar irregular histograms are obtained in scleromyxedema Arndt-Gottron and in Sclerodema adultorum Buschke. They are not specific for scleroderma. The irregularity and the shift of the histograms toward smaller diameters as well as the occurrence of filaments 100 Å thick and the locally increased amorphous ground substance point to productive activities which do not fit into the general atrophy of the cells. It is believed that the intercellular substances have been taken unawares by the atrophy in an indifferentiated or unincorporated state.