The follow-up of 43 patients with diffuse proliferative lupus nephritis is reported. After histological diagnosis, all patients were treated with 3 intravenous high-dose methylprednisolone pulses and then with low-dose oral steroids and 31 with cytotoxic drugs. Renal and extra-renal exacerbations were also treated with intravenous high-dose steroids. Patients were followed for 1 to 13 years. At 10 years the patient survival rate was 87% and the kidney survival rate was 79%. If 3 extra-renal deaths are excluded, the actuarial 10-year kidney survival rate is 91%. At present, 21 patients do not show any renal abnormalities, 13 patients have normal plasma creatinine but proteinuria, 3 patients have stable renal function impairment, 2 patients have worsening of their renal function, 1 is on regular dialysis. The other 3 patients died (from cardiac failure, cerebral hemorrhage and a car accident). The incidence of flare-ups was low (0.1 episodes per year). Severe side effects were rare in this series. It is concluded that the long-term prognosis of diffuse lupus nephritis is becoming considerably better. Therapy based on a short course of intravenous high-dose methylprednisolone and on a maintenance regimen with low doses of steroid and cytotoxic agents can contribute to preserving renal function while avoiding severe side effects.