Objective: To evaluate the safety and efficacy of nonmyeloablative preconditioning allogeneic hematopoietic stem cell transplantation (NMHSCT) in the therapy of unidentified relapse and primary solid tu-mors, and to study the anti-tumor immunity induced by the effect of Graft-Verus-Tumor (GVT). Methods: A to-tal of 13 difficult-to-treat cancer patients received NMSCT and the efficacy and side effects were observed. Re-sults: One case had CR, 2 cases had PR, 4 cases had SD, 5 cases had PD, and 1 case died of complica-tions associated with transplantation. One case was GVT (+++), 3 cases were GVT (++), 5 cases were GVT(+), and 4 cases were GVT (-). The main side effect was acute GVHD presented as diarrhea and infec-tion. VOD and brain disease were rare. Conclusion: Nonmyeloablative allogeneic stem cell transplantation is safe and effective for solide tumors.