Serum IgE was measured by RIST test in 181 adult subjects, with log transformation. In 24 controls the geometric mean was 109 IU/ml, with an upper limit (geometric mean +/- 2 SD) of 460 IU/ml. 157 cases of glomerulonephritis (GN) classified according to light and immunofluorescence microscopy were studied. Serum IgE was significantly elevated in 39 lipoid nephrosis patients (p less than 0.001, with 21 levels greater than 460 IU/ml), 21 focal and segmental glomerulosclerosis (p less than 0.05, with 8 levels greater than 460 IU/ml) and 42 membranous GN (p less than 0.01, with 10 levels greater than 460 IU/ml). In 27 membrano-proliferative GN and 28 IgA GN, serum IgE was not different from controls with respectively 4 and 3 levels greater than 460 IU/ml. In addition, the lipoid nephrosis IgE geometric mean is 493 IU/ml, which is keeping with the high incidence of atopic troubles. The significance of raised serum IgE was discussed.