Seven children with steroid-dependent nephrotic syndrome who were on stable remission under Sandimmun therapy were switched to Neoral at the same dosage. During the 4-month follow-up period, two patients relapsed, due to poor compliance in one of them. Serum creatinine remained stable in all patients. Pharmacokinetic profiles were performed at day 0 while on Sandimmun and 4 weeks after conversion to Neoral. Following conversion to Neoral, the peak concentration occurred earlier (2+/-1.4 h vs 3.9+/-2.4 h), and the maximum concentration (677+/-386 ng/ml vs 488+/-265 ng/ml) and the area under the curve (3,082+/-1,536 ng/ml/h vs 2,201+/889 ng/ml/h) were higher. We conclude that Neoral results in an increased bioavailability of cyclosporine (CsA) as compared to Sandimmun in patients with steroid-dependent nephrotic syndrome in remission.