The authors evaluate in a retrospective study the effect of prednisone, cyclophosphamide, small doses of acetylsalicylic acid, conventional antihypertensive drugs and ACE inhibitors on the course of primary chronic proliferative types of glomerulonephritis. The group comprised 44 patients, incl. 16 with normal blood pressure and 28 with hypertension. All were at first given prednisone and cyclophosphamide--for an average of 18 months--and the patients with systemic hypertension conventional antihypertensive drugs. At the termination of treatment proteinuria in the whole group was significantly lower, while glomerular filtration was unaltered, i.e. normal. When the results in normotonic and hypertonic patients were evaluated separately, it was obvious that normotonic patients have a significantly lower proteinuria and a glomerular filtration significantly higher than hypertonic patients. After termination of immunosuppression the authors started to administer to all patients acetylsalicylic acid (1/4 tablet Anopyrin in 24 hours) and in hypertensive patients the conventional antihypertensive drugs were replaced by ACE inhibitors, combined in some with Ca channel blockers. Antiaggregation therapy persists now for more than three years, treatment with ACE inhibitors for more than two years. The results at the end of the investigation indicate that there is no significant difference between normotonic and hypertonic subjects. All have proteinuria lower than 2.0 g/24 hours, stabilized glomerular filtration and after 15 years of glomerulonephritis none of the patients suffers from chronic renal failure. The authors assume that combined immunosuppression, antiaggregation therapy and treatment of hypertension with ACE inhibitors can contribute to the stabilization of chronic glomerulonephritis.