The association of membranous glomerulonephritis with carcinoma and minimal change disease with Hogkin's disease are well established. In contrast cancer and crescentic glomerulonephritis is an uncommon association. We report a patient with gastric carcinoma who developed synchronously acute renal failure due to crescentic glomerulonephritis. Corticosteroid therapy, plasma exchanges and tumor resection was associated with a regression of renal failure. Carcinoma must be considered as a possible cause of crescentic glomerulonephritis.