Background: The aim of the study was to evaluate the feasibility and efficacy of a non-myeloablative regimen to achieve complete donor chimerism after stem cell transplantation (SCT) in patients with metastatic solid tumors. Patients and methods: Seven patients with renal cell carcinoma (RCC), 3 with colorectal carcinoma and 1 with soft tissue sarcoma received an allogeneic SCT after fludarabine (90 mg/m2) and TBI 200 cGy. Results: At day 30, median donor chimerism was 94%. Regression of tumor metastases has been observed in 1 patient with RCC. Overall, 8 patients (73%) died from progressive disease (median progression-free survival 3.7 months) and 1 (9%) from treatment-related complications; 2 patients were alive 152 and 862 days after transplantation. Conclusions: Our preliminary results suggest that non-myeloablative SCT for metastatic solid tumors is feasible, although may lead to durable responses in a minority of patients. Careful patient selection seems to be mandatory in this transplant setting.