OBJECTIVE: To evaluate the efficacy and safety of mycophenolate mofetil (MMF) plus prednisone on refractory nephrotic syndrome (RNS) in children. METHODS: One hundred and forty-two children with RNS from ten clinical trial centers were divided into two groups: MMF (n=87) and control (n=55). The MMF group patients were administered with oral MMF (30-40 mg/kg daily) for at least 6 months. Afterwards the patients who responded to MMF received another 6 months MMF treatment at a dosage of 10-20 mg/kg daily. The controls were treated with pulse intravenous infusion of cyclophosphamide (CTX) (10 mg/kg daily) for 2 days every 2 weeks for 3 months. Then CTX was administered at a dosage of 500 mg/m2 once a month 4, 7 and 10 months after treatment. While the patients received MMF or CTX treatment, they were treated with oral prednisone (0.5-1 mg/kg daily) for 2 to 3 months, and then the dosage of prednisone was gradually reduced. Urinary protein, liver and renal functions, and side effects of drugs were examined at regular intervals for one year. RESULTS: Of the 87 patients, 58 achieved complete remission, 16 achieved partial remission, 9 achieved early remission and 4 had no response to treatment. In the control group, 35 achieved complete remission, 9 achieved partial remission, 1 achieved early remission and 10 had no response to treatment. The total remission rate in the MMF group (95.4%) was significantly higher than that in the control group (81.8%) (P<0.01). After treatment 67 patients (65.4%) in the MMF group had negative proteinuria compared with 36 patients (65.4%) in the control group (P>0.05). MMF was found to be more effective in reducing proteinuria, and improving hypoproteinemia, oliguria, hyperlipemia, and edema than CTX. MMF was better tolerated with lower incidences of adverse reactions than CTX. CONCLUSIONS: The combined therapy of MMF and prednisone is more effective and tolerable than pulse intravenous infusion of CTX for treatment of RNS in children.