A young woman presented with nephrotic syndrome due to membranous nephropathy and a localized form of giant lymph node hyperplasia (Castleman's disease) occurring as a large intra-abdominal mass. Five months after surgical removal of the mass, only mild proteinuria persisted. Twenty months later a second kidney biopsy showed a near-normal morphology. Six years later the patient was free of symptoms and had normal urinalysis. Reviewing the pertinent literature, it seems to be the first case of a biopsy-proven cure of membranous nephropathy in a patient with membranous nephropathy and Castleman's disease.