The serum levels of immunoglobulins G, A and M, C3, HBsAg and E rosettes were studied in 101 patients with various histologic forms of glomerulonephritis. The cell-conditioned immunity to antigens of glomerular basal membrane and RTE antigen were studied in 39 patients with glomerulonephritis and 53 patients with Balkan endemic nephropathy. Significantly increased serum levels of IgG, IgH and IgM were found as well as a decrease of the serum values of C3 in 40,6 per cent of the patients and circulating immune complexes in 47.5 per cent of them; 7 per cent of the patients were positive to HBsAg in serum. E-rosettes were significantly lower as compared with those of the healthy, in 46.5 per cent of the patients being under the norms. The cell conditioned immunity to GBM antigen was found in 53.8 per cent of the patients with chronic glomerulonephritis examined and to RTE antigen in 58.5 per cent of the patients with BEN. The changes found were interpreted as a disturbance in immune responses, characterized by the inhibition of T and activation of B cells, the presence of CIC, C3 reduction and high HBsAg percentage being an expression of that.