Advanced mycosis fungoides (MF) is incurable with conventional treatments. High-dose chemoradiotherapy with autologous bone marrow transplantation has induced remissions in a small number of patients with MF, but this modality is limited by a high relapse rate. We report induction of complete remission in a 37-year-old woman with rapidly progressive stage IV MF with allogeneic stem cell transplantation (Allo SCT). She remains in continuous complete remission 2 years after transplant. Allo SCT for MF is theoretically attractive, because there is no contamination of the graft by malignant cells, and because of the possibility of graft-versus-tumor effect. Although the results in this patient are encouraging, more patients and longer follow-up are needed to define the usefulness of Allo SCT in the treatment of MF. (J Am Acad Dermatol 2002;47:140-5.)