The evaluation of hematologic disorders after solid organ transplantation (SOT) must take into account issues unique to the post-transplant setting that influence the development of anemia and single or multi-lineage cytopenias. Attention to the time of onset of cytopenia(s) is important, because the disorders of passenger lymphocyte syndrome, transplant-related thrombotic microangiopathy, hemophagocytic syndrome, and graft-versus-host disease typically occur during the first few months after SOT, and post-transplant lymphoproliferative disorder usually occurs within the first year. Drug-related anemia and cytopenia(s) occur due to a variety of mechanisms, including drug-induced hemolysis and marrow suppression and perturbation of T-cell subsets by the immunosuppressive agents, leading to immune dysregulation and autoimmunity. Viral infections can cause direct suppression of hematopoiesis, and a variety of opportunistic infections can precipitate acquired hemophagocytic syndrome, a frequently lethal systemic inflammatory disorder. Early investigation of pancytopenia by bone marrow biopsy is warranted, because it is often the presenting symptom of one or multiple life-threatening pathologies after SOT, such as graft-versus host disease, post-transplant lymphoproliferative disorder, hemophagocytic syndrome, or severe opportunistic infections, and these entities may have a better prognosis if early interventions are undertaken.