To determine whether intravenous immunoglobulin (IVGG) would be an efficacious adjunct in the treatment of childhood minimal change nephrotic syndrome (MCNS), we enrolled ten patients with frequently relapsing or steroid-dependent MCNS in a double-blind crossover clinical trial. At the time of relapse of the nephrotic syndrome, patients were assigned to treatment with a single outpatient infusion of IVGG (800 mg/kg) or intravenous albumin as a control. The relapse was treated concurrently with standard doses of oral prednisone. At the time of the next relapse, patients who had first received IVGG were treated with albumin, and vice versa. There were no significant differences in the length of remission between the IVGG and albumin treatments. The study had a power of 0.72 to detect a true difference of 45 days between the two therapies. We conclude that in the dose of drug used in this trial, administered at the time of relapse in conjunction with prednisone therapy to children with frequently relapsing or steroid-dependent MCNS, IVGG does not lead to a clinically important extension of the period of remission.