In order to clarify the T-cell abnormalities present in minimal-change nephrotic syndrome (MCNS), lymphocyte subsets were studied using two-color flow cytometry in children with MCNS and nephrotic syndrome caused by other types of glomerular disease, and normal healthy children. In MCNS, CD4+ Leu8+(suppressor-inducer) and CD3+ CD25+(IL-2 receptor positive T) cells were significantly increased, and CD4+ Leu8-(helper-inducer), CD8+ CD11+(suppressor), CD3+ HLA-DR+(DR positive T) and CD4+ HLA-DR+(activated helper/inducer) cells were significantly decreased in comparison with normal healthy children. The same abnormalities were also found in nephrotic syndrome caused by other types of glomerular disease. These findings indicate that abnormalities of lymphocyte subsets are present in MCNS and nephrotic syndrome due to a variety of glomerular diseases, and suggest that such abnormalities are a consequence of nephrotic syndrome.