The distribution of fibronectin (FN) was studied in skin biopsies of 13 patients with scleroderma (SD), 7 patients with dermatomyositis (D), and 10 normal controls (NC) by direct immunofluorescence. In normal tissues, continuous or segmental linear staining of the dermal-epidermal junction (DEJ) was seen. Papillary, subpapillary dermis, and papillary capillary loops showed a reticular pattern of deposition with fibronectin. Scleroderma patients revealed similar staining in the dermis and DEJ. The reticular distribution of FN appeared to stain more intensely in the dermis than in controls, especially in deeper layers. The amount of FN in walls of blood vessels from SD patients was markedly increased; all dermal vessels stained with FN and revealed considerably thicker walls and larger lumens. FN distribution in DM patients was similar to that seen in SD with an increased amount of FN staining in capillary walls.