Bone Marrow Transplantation (BMT), also known as stem cell transplantation, is a critical treatment for a variety of hematologic diseases, including leukemia, lymphoma, myeloma, and non-malignant conditions like aplastic anemia. The procedure involves replacing a patient's diseased or damaged bone marrow with healthy stem cells, which are capable of producing new blood cells. The transplanted stem cells can come from the patient’s own body (autologous transplant) or from a matched donor (allogeneic transplant). Autologous transplants are commonly used in diseases like multiple myeloma or lymphoma, while allogeneic transplants are typically reserved for diseases such as acute leukemia or myelodysplastic syndromes. Bone marrow transplantation is typically preceded by high-dose chemotherapy or radiation therapy, which is used to destroy the patient’s existing marrow and prepare the body to accept the new stem cells. The engraftment process, where the transplanted stem cells begin to grow and produce new blood cells, can take weeks to months, and during this period, patients are at high risk for infections and other complications. Post-transplant care is crucial and includes infection control, immunosuppressive therapy to prevent graft-versus-host disease (GVHD) in allogeneic transplants, and regular monitoring of blood counts and organ function.