In idiopathic membranous nephropathy (IMN) immunosuppressive therapy should be reserved for patients with potential risk factors at baseline or who show a progressive course. Cyclophosphamide pulse therapy (CPT) in IMN is not yet widely tested. We carried out a trial of CPT combined with conventional treatment in a group of patients with IMN at a greater risk. The study group consisted of 36 nephrotic adult IMN patients (M, 26; F, 10) with various combinations of risk factors. Mean proteinuria was 11.3 g/day, 47% patients were hypertensive, 78% had tubular changes, and 36% had focal glomerulosclerosis. They were treated with CPT and/or conventional low-dose cyclophosphamide and prednisolone. Median duration of immunosuppression was 14 months and median total cumulative dose of cyclophosphamide 172 mg/kg body weight. At 6 months (6m) remission was achieved in 44% cases and at the 36th month in 73%. None of the patients developed moderate or severe renal failure. Side-effects were minimal. Multivariate analysis of baseline data and the changing course of the disease during therapy showed that tubular changes (P = 0.0025), creatinine clearance at baseline (P = 0.04) and at 6m (P = 0.02), and proteinuria at 6m (P < 0.0001) significantly influenced the therapeutic effect. We conclude that cyclophosphamide (including pulse) and prednisolone can bring significant remission and maintain renal function in IMN with potential risk factors.