Altogether 67 patients with chronic glomerulonephritis (CGN) were examined for the content of thymus-dependent precursor lymphocytes (auto-RFC, pre-T-cells). The patients suffering from CGN were characterized by the high content of the young post-thymic T-cells (auto-RFC) and high affinity T lymphocytes carrying a receptor for the Fc fragment of IgM as compared to normal donors. In patients with different clinical patterns of CGN, an analysis was made of the content of precursor thymus-dependent lymphocytes. A relationship was discovered between the content of pre-T-cells and the activity of the nephritic process. The activity of the pathological process was associated with the high content of precursor lymphocytes. The inactive course of nephritis was characterized by a well-defined reduction of the number of precursor cells. This might be regarded as depletion of the amount of precursor lymphocytes.