Abstract: Ohjective: To investigate the curative effect of intermittent venous injection of high dosage of cyclophosphamide (CTX) on serious lupus nephritis. Method: 146 patients with lupus nephritis were divided into three groups. There are 56, 46, and 44 patients in group A, B, and C, respectively.The treatment of group A was venous injection of CTX plus oral prednisone (1mg. kg-1/d). Group B took prednisone (1. 5mg. kg- 1/d), orally. If patients had active lupus they simultaneously accepted injection of methylprednisolone (1g/d ) three days per week, in the other four days they took prednisone (1. 5mg. kg- 1/d). The method may be repeated two to three times. Group C took prednisone (1～1. 5mg. kg-1/d) ) and CTX (2mg. kg-1/d) orally. The treatment took 2 months. Results: The patients in all three groups got their immunological abnormalities improved, proteinuria decreased and renal function increased. There was no statistic significance of the treatment among the three groups, but the side effects of the treatment had the statistic significance in three groups. The side effects in group A was the least,some patients has the minor and temporary symptoms of gastrointestinal tract. The secondary infection was the highest. The liver damage and white blood cell decrease in group C was more serious than in other groups. Conclusions: High dosage CTX injection in treatment of serious lupus nephritis can decrease proteinuria and improve renal function, and has the same curative effects as oral prednisone or CTX, but the method has less side effects than oral prednisone or CTX.