The treatment of membranous nephropathy, the most common form of glomerular diseases causing nephrotic syndrome in adults, is still debated. A considerable percentage of patients have a spontaneous remission of the disease and reduction of urinary protein excretion with time. Studies in the past have indicated that prednisone may have beneficial effects, but this has not been confirmed by more recent investigation. Others have studied the association of methylprednisolone with cyclophosphamide or chlorambucil, but results are conflicting. The main reasons for the conflicting data are the variety of clinical presentations of the disease and the different study populations. Most trials performed so far have not included enough patients in each category to adequately detect differences between treatment groups and placebo groups. Several studies with few numbers of patients reported that cyclosporine effectively reduced proteinuria and may have less long-term toxicity than more conventional immunosuppressants. This finding, however, must be verified by appropriate clinical trials.