Hematopoietic stem cell transplantation, known commonly as bone marrow transplantation, is a complex medical procedure. This procedure replaces damaged or destroyed bone marrow with healthy hematopoietic stem cells. This treatment can be lifesaving for patients with conditions such as leukemia, multiple myeloma, and lymphoma, as well as for individuals with severe blood diseases like aplastic anemia. The procedure involves two main types: autologous transplantation, where the patient’s stem cells are used, and allogeneic transplantation, which involves stem cells donated by a genetically compatible donor. The process includes the preparation phase, where the patient may receive chemotherapy or radiation to eliminate the diseased marrow, followed by the transplantation of hematopoietic stem cells. These transplanted cells then migrate to the bone marrow and produce healthy blood cells. While bone marrow transplantation can be highly effective, it also carries risks of complications, including infections and graft-versus-host disease, where donated cells attack the recipient’s body.