Post-transplant lymphoproliferative disorder is a rare and serious complication of organ and stem cell transplant secondary to immunosuppressive therapies, most commonly of monomorphic B-cell subtype. Here we describe the first reported case of a pediatric heart transplant patient who developed both monomorphic B-cell and nondestructive PTLD with plasmacytic hyperplasia followed by an unrelated case of monomorphic T-cell and nondestructive PTLD with plasmacytic hyperplasia, which later relapsed. We detail the patient’s risk factors for development of PTLD and her successful treatment regimens. This case highlights the potential relationship between Epstein-Barr virus and/or cytomegalovirus and PTLD.