The results of clinical, functional and renal biopsy follow-up studies performed in 2 series of adult patients with glomerulonephritis are reported. The first series included 35 cases which were divided into 4 groups according to the histological picture, namely cases with ‘minimal’, ‘proliferative’, ‘membranous’ and ‘chronic’ lesions. These cases were treated with Azathioprine alone (16 cases) or combined with prednisone (19 cases) for 1 to 2 years. A true recovery-rate (based on the disappearance of the clinical, biochemical and renal biopsy lesions) was found in 31,4% of the cases. The second series consisted of 15 immunosuppressive-resistant cases. A lymphatic depletion was obtained by Thoracic Duct Fistula, and was estimated as satisfactory in 11 of the cases with an average output per fistula of 50 × 109 lymphocytes and 36,91 g of immunoglobulins. Post-fistula immunosuppressive therapy was in each case the same as the pre-fistula one. Three cases completely recovered, 4 cases improved, 4 cases were unchanged. Some hypotheses able to account for the observed resul