Twenty-five renal biopsies from patients with Henoch--Schönlein nephritis were examined using light microscopy, immunofluorescence, 1 micrometer plastic-embedded sections and electron microscopy. The 1 micrometer plastic-embedded sections and electron microscopy showed deposits in mesangial, subendothelial and subepithelial sites. Some of the latter were very large and similar to those which have been described as "humps" in acute proliferative glomerulonephritis. Immunofluorescence showed the mesangial deposition of IgG, IgA and C3 with extension into a peripheral position in some cases. Fibrin was frequently found associated with crescents. The case for Henoch--Schönlein disease being mediated, in part at least, by immune complex deposition, is presented.