Background. Posttransplant lymphoproliferative disorders (PTLDs) occur after solid organ transplantation. Treatment guidelines include reduction in immunosuppression (RIS), radiation, rituximab, chemotherapy, and immunological agents. We present a rare case of recurrent diffuse large B-cell lymphoma presenting as a PTLD in a heart transplant patient treated with autologous blood stem cell transplant (ASCT) after failure of conventional therapy. Case Presentation. A 66-year-old male presented with a neck mass. He has a history of Hodgkin's disease status after staging laparotomy with splenectomy and heart transplantation due to dilated nonischemic cardiomyopathy 8 years prior to the development of PTLD. His examination was remarkable for right submandibular swelling. An excisional biopsy confirmed the diagnosis of diffuse large B-cell NHL. Patient received RIS, rituximab, chemotherapy, and radiation therapy with a complete remission. His lymphoma relapsed and he subsequently was treated with RICE salvage chemotherapy and consolidative high-dose chemotherapy with BEAC regimen followed by ASCT resulting in a complete remission. Conclusion. Patients with PTLD present a difficult therapeutic challenge. In this case, the patient's prior history of Hodgkin's disease, splenectomy, and a heart transplant appear to be unique features, the significance of which is unclear. ASCT might be a promising therapy for patients with relapsed or refractory PTLD.