T prolymphocytic leukemia (T-PLL) is an unusual disease characterized by high white cell counts, older age at presentation, splenomegaly and a very aggressive clinical course. We describe a 47-year-old male with refractory T-PLL who was treated with high-dose chemoradiotherapy and allogeneic bone marrow transplantation (BMT) from an HLA-matched sibling. The transplant was complicated by both acute and chronic graft-versus-host disease (GVHD). The patient achieved complete remission and remains in remission 3 years after the transplant.