Patients with bioptically ascertained glomerulonephritis of the years 1969-1981 were examined. At the time of the kidney biopsy etiology, onset of the disease and data of the findings were evaluated. Moreover, in 160 out of 300 patients after-examinations were performed. Especially also the examination of patients with erythrocyturia was carried out with the help of the phase contrast microscopy. In a second part of the examinations which we report on 2 therapy studies were performed. In the first therapy study the effectiveness of the therapy with prednisolone (n = 33), prednisolone + cytostatic drug (n = 43) as well as the indomethacin treatment (n = 52) in patients with and without nephrotic syndrome was examined. We found that an initial prednisolone dose of more than 50 mg/die for at least over 1 month is more successful than a low prednisolone dose. Indomethacin has no clinically provable therapeutic effect in the nephrotic syndrome. In normal renal function the duration of the disease has no ascertained influence on the results of the therapy. In the second therapy study the effectiveness of the CAA- (n = 27) and the CAAP-therapy, respectively, (n = 98) (cytostatic drugs, anticoagulant drugs, thrombocyte aggregation inhibitors and prednisolone) was investigated. The results of the therapy depending upon the clinical course and the morphological findings revealed that there is an indication to the CAA-CAAP-therapy in nephrotic syndromes in glomerulonephritis with and without sclerosation as well as in glomerulonephritis with relapsing exacerbations with and without sclerosations. No indication for this therapy is given in chronic courses of glomerulonephritis with slight proteinuria and in nephrotic syndromes with hypertension.