A 62-year-old white male suffering from plasmacytosis with monoclonal gammopathy developed gastrointestinal bleeding, microscopic hematuria, proteinuria and progressive azotemia. A renal biopsy demonstrated capillary wall thickening, mesangial hyperplasia, crescent formation and subepithelial humps. Serum immunoglobulin analysis showed IgG of lambda type. Serum complement, ANA, ASO titer and cryoglobulin were normal. It is suggested that proliferative glomerulonephritis with subepithelial humps should be added to forms of renal pathology that can be seen in plasma cell dyscrasias.