Membranous nephropathy is a histological appearance which indicates a particular immunopathogenesis, but may have many basic aetiologies and is probably not a single disease. It is predominantly an appearance seen in middle-aged and elderly individuals, and in general has a slow progression over years or even decades towards remission or renal impairment in almost equal proportions. An aggressive search for associated disease is worthwhile, and one should wait to see what the evolution of proteinuria and renal function may be. If a progressive course becomes evident, then a trial of treatment with corticosteroids is worthwhile, but if this is ineffective, a more aggressive approach involving the use of alkylating agents may be justified. Cyclosporin does not appear to have a major effect in the majority of patients, and intravenous gammaglobulin is under evaluation at the moment with some encouraging results. The best treatment regime remains to be determined.