Allogeneic hematopoietic stem-cell transplantation can induce curative graft-versus-leukemia reactions in patients with hematological malignancies. There is also evidence of such an effect in patients with solid tumors. We report two patients with metastatic renal cell carcinoma who underwent RIST. In both patients, disease progression was observed 6 months after transplantation. However, one patient had transient symptoms of tumor progression after the occurrence of acute graft-versus-host disease, consistent with graft-versus-tumor effects.