A 59-year-old female with an unresectable, large pancreatic tumor (10.0 x 8.0 cm(2) on CT scan) underwent nonmyeloablative allogeneic peripheral-blood stem-cell transplantation from her HLA-identical sibling. Pronounced tumor regression and relief from pain without acute graft-versus-host disease (GVHD) were observed following transplantation. The patient is surviving (more than 300 days) after transplantation, with extensive chronic GVHD, and has tumor regression with an 80% reduction in tumor size. The observed clinical course may suggest a graft-versus-tumor effect on the pancreatic tumor following allogeneic stem-cell transplantation.