One hundred and fourteen children with primary nephrotic syndrome were followed up prospectively for periods of between 5 and 14 years. Urine samples from 94 of them became protein-free during the initial 8-week course of prednisone, and the outcome for these children was good: 74 of them have been free of symptoms for at least 3 years, 18 have had relapses during the last 3 years, and only one child still has proteinuria. All these children have normal renal function and blood pressure. One child died accidentally. Twenty children did not respond to the initial prednisone treatment. Thirteen of them had remissions later, of whom 2 have had relapses during the last 3 years. Seven were totally resistant to prednisone 4 of whom died in renal failure, the remaining 3 have persistent proteinuria with normal levels of creatinine; one has high blood pressure too. Remission during the initial treatment indicated a good prognosis, but two-thirds of the initial non-responders also fared well.