We report the effect of 18-month ciclosporin (CS) treatment in 19 children with steroid-dependent frequently relapsing nephrotic syndrome. CS was started at 3-5 mg/kg per day after remission with steroid therapy, was adjusted to maintain a trough blood level of between 200 and 600 ng/ml and was administered for 6 months (high-dose CS). Then, the dosage of CS was decreased and 2.5 mg/kg per day was administered for the subsequent 12 months (low-dose CS). Only 2 patients had relapses during the initial 6 months of CS therapy. Eight patients had infrequent relapses, 4 had frequent relapses and 7 had no relapses during the 12 months of low-dose CS. Not only did continuation of CS at a lower dosage decrease the relapse rate, it also reduced steroid toxicity, allowed increased growth in 16 of the 19 patients and also decreased obesity scores in 12 of these patients. All of the side-effects that occurred during the 18-month period of CS treatment were reversible and none was serious enough to necessitate discontinuation of therapy. Our 18-month CS treatment was helpful in preventing relapses and reducing steroid toxicity in children with steroid-dependent frequently relapsing nephrotic syndrome.