Idiopathic myelofibrosis is characterized by bone marrow fibrosis, anemia, leukoerythroblastosis, and extramedullary hematopoiesis in many organs. Renal abnormalities in idiopathic myelofibrosis have been rarely described in the literature and include extramedullary hematopoiesis in the pararenal or retroperitoneal areas resulting in obstructive uropathy and hemtopoietic cell infiltration in tubulointerstitial area and urolithiasis. These lead to azotemia or acute renal failure, which may respond well to radiotherapy and adjuvant chemotherapy. To our knowledge, there has been only one case report of nephrotic syndrome associated with glomerulonephritis in a myelofibrosis patient; however, no effective treatment was described. Herein, we report the case of a patient with idiopathic myelofibrosis who initially presented with hepatomegaly, anemia, and leukoerythroblastosis. A nephrotic syndrome developed 7 years after initial diagnosis. Renal biopsy disclosed the unique pathological finding of simultaneous mesangial proliferative glomerulonephritis, renal extramedullary hematopoiesis, and gouty nephropathy. Despite treatment with busulfan, proteinuria persisted that implied irreversible glomerular injury and a terminal prognosis. We focus on the unusual pathological finding and the association between nephrotic syndrome and idiopathic myelofibrosis.