We have studied 32 patients with idiopathic nephrotic syndrome aged from 3 to 59 years. The clinical course of 20 patients with IgM mesangial deposits was compared with that of 12 patients without glomerular immune deposits. The presence of IgM deposits seems to be unrelated to any particular clinical onset, histological pattern on light microscopy, therapy response, or clinical course in our relatively short follow-up. The conclusion from this study is that IgM mesangial deposition is not a marker for response to therapy in patients with idiopathic nephrotic syndrome.