A case of isolated testicular relapse occurring 5 years after allogeneic bone marrow transplantation (BMT) for acute myelogenous leukemia (AML) is reported. The patient presented with M4 AML at age 13 and underwent allogeneic BMT in first remission, 5 months after diagnosis. He had no acute graft-versus-host disease (GVHD) but developed mild chronic GVHD 5 months following transplant and received immunosuppressive therapy for the next 2 years. Five years post-transplant he had an isolated testicular relapse that was treated with chemotherapy and testicular radiation. The patient remains in remission 17 months following relapse and more than 15 months following the cessation of therapy.