Stem cell transplantation, commonly known as a bone marrow transplant, is a medical procedure that replaces unhealthy blood-forming cells with healthy ones. This procedure allows doctors to deliver high doses of chemotherapy or radiation therapy, thus increasing the chances of eradicating blood cancer from the marrow, followed by the restoration of normal blood cell production. The underlying principle of stem cell transplantation is that blood cells and immune cells derive from stem cells, which are found in the marrow, peripheral blood, and cord blood. Intense chemotherapy or radiation therapy eliminates the patient's stem cells.