The purpose of the study was to assess the intensity of lymphocyte T apoptosis in nephrotic children's peripheral blood before, during and after the treatment with prednisone. The percentages of apoptotic lymphocyte T were determined by flow cytometry using annexin V. The study comprised 26 nephrotic children aged 3-14 years. The controls were 15 healthy children. In acute phase of the nephrotic syndrome before institution of the therapy the mean percentage of apoptotic lymphocytes T was 2.61%. It was significantly higher than that in controls (1.08%). During treatment with prednisone a statistically significant increase in the mean percentage of apoptotic lymphocytes T was observed. After four-week therapy with prednisone and after completion of the treatment the percentages of apoptotic lymphocytes T were 7.96% and 9.51%, respectively. They were significantly higher than those in patients before treatment and in healthy children.