Patients with metastatic melanoma have a very poor prognosis despite contemporary biochemotherapy. A 14-year-old girl with stage IV melanoma and brain metastasis received a nonmyeloablative conditioning and a hematopoietic graft from an HLA-identical sibling. She had progression of disease in the first 2 months after transplantation. After withdrawal of immunosuppressant and establishment of a full donor chimeric status, peripheral disease response was documented by regression of metastatic disease and lack of tumor progression until 1 year after transplantation. She died of progressive disease 21 months after diagnosis and 17 months after transplantation. Her clinical course suggested the possible existence of an allogeneic graft-versus-melanoma response that prolonged her survival.