Posttransplant lymphoproliferative disorders (PTLDs) may occur as a complication of immunosuppression in patients who have received solid organ or bone marrow allografts. Most PTLDs are of B-cell lineage, whereas T-cell proliferations are rare. The majority of B-cell lesions are associated with Epstein-Barr virus infection. The occurrence of both B-cell and T-cell PTLDs in the same patient is extremely rare and only 6 cases have been previously published. We report a case of a 63-year-old man who developed 2 metachronous Epstein-Barr virus-related PTLDs beginning 10 years after heart transplantation. A polymorphic B-cell PTLD developed first that completely regressed after immunosuppressive therapy was partially withdrawn. Then, a monomorphic T-cell PTLD developed 31 months later. The patient died 17 months later owing to disease progression. We highlight the diagnostic challenge of this case that required numerous ancillary studies for lineage assessment and classification. Such studies are often needed in patients with a history of immunosuppression.