Coulter flow cytometry was used to determine glucocorticoid receptors (GCR) in the peripheral blood cells of patients with nephrotic syndrome. The expression of GCR in the lymphocytes (CD3/GCR) and monocytes (CD14/GCR) of peripheral blood of 23 (age 4.9+/-2.7 years) children with steroid-sensitive nephrotic syndrome was assessed before treatment (proteinuria >50 mg/kg per 24 h), after 4-6 weeks of prednisone treatment, without proteinuria, and in remission, without proteinuria and without any treatment. Before treatment the expression of CD3/GCR was 61.8+/-18.3% and CD14/GCR 43.6.8+/-20.3%; this did not differ from the results of the normal control group ( P>0.05). However, after treatment GCR expression in lymphocytes was 50% ( P<0.001) and in monocytes about 20% lower ( P<0.05). In remission, the GCR expression increased and did not differ from the results before treatment ( P>0.05). A positive correlation between the serum cortisol concentration and the expression of CD3/GCR was found ( r=0.504, P=0.02). In summary, we report that in children with steroid-sensitive nephrotic syndrome, prednisone treatment causes the temporary decrease of the expression of GCR in lymphocytes. A positive correlation between GCR expression and serum cortisol was found. A decrease in GCR expression in monocytes did not correlate with cortisol concentration.