Renal morphology was evaluated in 2 siblings with Wiskott-Aldrich syndrome (WAS) aged 12 and 4 years. They gave a typical history of recurrent episodes of respiratory infection and presented with microhematuria of glomerular origin and proteinuria. The study disclosed a membranoproliferative glomerulonephritis with IgA mesangial deposition in the elder child, while immunofluorescence was negative in the younger. The data indicate that (1) a specific nephropathy does not exist in WAS and (2) the IgA nephropathy is the result of recurrent infections and of related formation of IgA immune complexes scarcely removed by a deficient reticuloendothelial system. This view is consistent with presenting features in WAS (microhematuria, episodes of macrohematuria, proteinuria, Henoch-Schönlein syndrome) and with the fact that it takes years to develop as indicated by the negativity of immunofluorescence in the younger patient.