A 63-year-old woman was diagnosed as having multiple myeloma (MM), IgG-kappa type, stage IIIA, in October 2003. She achieved partial response after receiving three courses of VAD therapy and one course of high dose dexamethasone therapy (HDD); maintenance therapy consisted of melphalan and prednisolone. In November 2004, the patient developed spinal canal stenosis that required surgery. At the end of December 2004, the patient developed renal dysfunction that progressed to anuria. A CT scan showed multiple retroperitoneal masses that impinged on and obstructed both ureters and caused bilateral hydronephroses. Renal function improved after a right percutaneous nephrostomy and chemotherapy consisting of HDD, cyclophosphamide, vincristine, and doxorubicin. Nevertheless, the patient died due to MM in February 2005. On autopsy, multiple retroperitoneal and pelvic plasmacytomas with 13q- and t(4;14) (p16;q32) were found. Our patient is a rare case that, in the terminal stage of MM, developed aggressive phase multiple myeloma with extramedullary plasmacytomas that caused acute renal failure due to compression on both ureters.