Why it's done

Every year, thousands of people in the U.S. are diagnosed with life-threatening diseases, such as leukemia or lymphoma, for which a stem cell transplant is the best or the only treatment. Donated blood stem cells are needed for these transplants.

You might be considering donating blood or bone marrow because someone in your family needs a stem cell transplant and doctors think you might be a match for that person. Or perhaps you want to help someone else — maybe even someone you don't know — who's waiting for a stem cell transplant.