A patients physician begins a preliminary search of the National Marrow Donor Program (NMDP) Registry.

A list of potential matches (donors whose HLA-ABDR antigens match the patient) are sent to the physician, who requests further testing of the donors blood.

From these results, the physician determines whether there is a match.

If a match is found, the patient undergoes pre-transplant conditioning, consisting of radiation and chemotherapy, for seven to ten days.

The donated marrow is transfused directly into the patients blood stream, much like a blood transfusion. Healthy marrow cells travel to bone cavities, where they begin to grow and replace the old marrow.

The patient must be isolated in a germ-free environment until the new marrow produces enough white blood cells to fight off disease.

An increased white blood count, a sign that the transplant is beginning to function, generally appears about three to four weeks after the procedure.