We report our experience with ciclosporin (CS) treatment in 18 children with steroid-dependent nephrotic syndrome. CS was started at 3-5 mg/kg per day after the patients had attained remission with steroid therapy, and was adjusted to maintain a trough blood level of between 250 and 600 ng/ml, being administered for 6 months. Although 1 patient dropped out of the study because of renal dysfunction, the remaining 17 children completed the full trial. No relapse occurred during the 6-month period of CS treatment, and it was possible to discontinue steroid therapy in all patients. However, after discontinuation of CS treatment, nephrotic syndrome relapsed in 16 patients and 14 again had frequent relapses and became steroid-dependent, as before CS treatment. The effect of CS in maintaining remission from steroid-dependent nephrotic syndrome was thus dependent on continuation of CS treatment. Although several side-effects occurred during CS treatment, they were not so serious as to necessitate discontinuation of treatment, except in 1 patient, and all of these side effects were reversible. CS is therefore a new agent for the management of children with steroid-dependent nephrotic syndrome in place of corticosteroid and alkylating agents, although long-term maintenance therapy may be necessary for maintaining longer remission.