The variable response of patients with idiopathic nephrotic syndrome (NS) to glucocorticoid (GC) treatment has not been explained. Earlier studies indicated that the response is limited by cellular GC receptors. We investigated these receptors in mononuclear leukocytes of 28 pediatric patients with NS divided into three groups: steroid-sensitive in relapse, steroid-sensitive in remission, and steroid-resistant. Density and binding affinity of GC receptors were determined by a dexamethasone binding assay; no significant differences were found between the three patient groups and between these and healthy controls, although a few patient values fell outside the range of controls. Total and free plasma concentrations of cortisol were low in all three patient groups. A weak positive correlation was found between the number of GC receptors and total plasma cortisol (r=0.36, P=0.03). The results suggest that factors other than GC receptors that mediate the cellular effects of GC are involved in the variable response of NS patients to GC.