Eight and 12 week courses of cyclophosphamide in nephrotic syndrome Seventy-three children with steroid dependent minimal change nephrotic syndrome were randomly allocated to receive treatment with cyclophosphamide (2 mg/kg/day) for either eight or 12 weeks, in combination with prednisolone. All patients had previously relapsed while the dosage was being reduced or within 14 days of discontinuing prednisolone in the six months before receiving cyclophosphamide treatment (steroid dependent), and had severe steroid toxicity. Thirty two patients were treated with cyclophosphamide for eight weeks, and 41 for 12 weeks. There were no differences between the two groups in age at onset of nephrosis or entry into the study, sex ratio, duration of nephrosis, number of relapses before entry, and follow up period after entry. The relapse free rate of patients treated for eight weeks (25%) was similar to that of those treated for 12 weeks (24%) five years after stopping the treatment, and the mean relapse free interval and the sparing effect of cyclophosphamide (if any) on subsequent treatment with steroids did not differ between the groups. We conclude that cyclophosphamide should be used for no longer than eight weeks at a dose of 2 mg/kg/day in children with steroid dependent minimal change nephrotic syndrome. 