Membranous lupus nephritis (MLN) represents about 20% of clinically significant renal disease in lupus. Few studies have addressed directly the pathogenesis of MLN. Our assumptions about the underlying mechanisms are based on the combination of extrapolations from idiopathic membranous nephritis (mainly from animal models) and proliferative lupus nephritis. Natural history studies of MLN suggest a relatively low rate of progression to end-stage renal disease but a high rate of significant comorbidities. Historical changes in the criteria for pathologic diagnosis and classification of membranous lupus nephropathy have precluded definitive descriptions of the natural history, prognosis and treatment of this disorder. Patients with membranous lupus nephropathy should be treated early with angiotensin antagonists to minimize proteinuria, as well as lifestyle changes and appropriate drugs to reduce attendant cardiovascular risk factors. In patients with protracted nephrotic syndrome, consideration should be given to immunosuppressive therapies, including corticosteroids, cyclosporine, mycophenolate and cyclophosphamide. Prospective controlled trials are clearly needed in order to establish solid clinical practice guidelines for use of these drugs and other experimental therapies currently under study in membranous lupus nephropathy.