A 52-year-old man, who had been diagnosed as having alcoholic liver cirrhosis, presented a chronic nephritic syndrome due to hepatic glomerulosclerosis. Ten months before death, massive proteinuria exceeding 40 g/day was noted. A renal biopsy revealed diffuse mesangial sclerosis, associated with an IgA deposition consistent with hepatic glomerulosclerosis. Although the nephrotic syndrome subsided with immunosuppressive therapy, he died of hepatic failure. Postmortem examinations disclosed a diffuse, medium-size B-cell lymphoma, involving the peritoneal and retroperitoneal organs and an IgA-positive plasmacytosis. His massive proteinuria seems to have been caused by the paraneoplastic syndrome of a malignant lymphoma.