Metastatic renal-cell carcinoma (RCC) remains resistant to nearly all standard cytotoxic therapies, but immune-based cytokine therapies benefit a small minority of patients with advanced RCC. Nonmyeloablative allogeneic stem-cell transplantation is a novel approach to harnessing the immune system to combat this cancer. The strategy relies on a T-cell graft-versus-malignancy effect mediated by donor T cells. Preliminary work in using nonmyeloablative allogeneic stem-cell transplant in RCC has identified a graft-versus-RCC effect and yielded encouraging clinical responses.