Post-transplant lymphoproliferative disorders (PTLDs) are serious, life-threatening complications of solid-organ transplantation (SOT) and bone marrow transplantation, and are associated with high mortality. PTLDs represent a heterogeneous group of lymphoproliferative diseases, which show a spectrum of clinical, morphologic, and molecular genetic features ranging from reactive polyclonal lesions to frank lymphomas. We describe clinicopathologic features of 17 cases of PTLD after allogeneic hematopoietic stem cell transplantation (allo-HSCT), which were analyzed by in situ hybridization for EBV and a panel of antibodies directed against numerous antigens, including CD20, PAX5, CD3, bcl-6, CD10, MUM-1/IRF4, CD138, Kappa, Lambda, CD30, CD15, and Ki67. The cases included 13 males and 4 females with a median age of 31 years (range 9-49 years) and the PTLDs developed 1.5-19 months post-transplant (mean 4.7 months). The histological types indicated five cases of early lesions, two of plasmacytic hyperplasia and three of infectious mononucleosis-like PTLD. Eight cases were polymorphic PTLD, and four were monomorphic PTLD, including three of diffuse large B cell lymphoma, and one of plasmablastic lymphoma. Foci and sheets of necrosis were observed in five cases. The infected ratio of EBV was 88.2 %. Some cases were treated by reduction of immunosuppression, antiviral therapy, donor lymphocyte infusion, or anti-CD20 monoclonal rituximab. Eight cases died. The first half year after allo-HSCT is very important for the development of PTLD. The diagnosis of PTLD relies on morphology and immunohistochemistry, and EBV plays an important role in the pathogenesis of PTLD. The prognosis of PTLD is poor, and, notably, PTLD after allo-HSCT exhibits some features different from those of PTLD after SOT.