Registering to donate bone marrow takes about 10 minutes online and involves swabbing your cheeks at home with a free kit mailed to your door. The process is managed in the U.S. by NMDP (formerly the National Marrow Donor Program), and joining costs nothing. Once registered, you stay on the donor list until age 61, ready to be contacted if your tissue type matches a patient in need.
How to Join the Registry
Start by visiting the NMDP website and filling out a brief health questionnaire. If you meet the basic requirements, you’ll be mailed a cheek swab kit at no cost. The kit includes two sterile swabs, barcode labels, detailed instructions, and a prepaid return envelope.
When the kit arrives, the process is straightforward. Avoid eating or drinking for 30 minutes before you swab. Wash your hands, then firmly swab the inside of one cheek for 10 seconds and repeat on the other cheek with the second swab. Wrap a barcode label around the handle of each swab so the lab can identify your samples. Let both swabs air dry for two to five minutes, then place them in the return packaging with the swab tips pointing left and barcodes facing up. Seal the prepaid envelope and drop it at any USPS mailbox or post office.
Your DNA is then analyzed to determine your tissue type, specifically a set of genetic markers called HLA (human leukocyte antigens). These markers on the surface of your cells are what doctors use to find a compatible match for a patient. For unrelated donors, four key HLA markers are evaluated, and a perfect 8-out-of-8 match is the goal. Your HLA profile goes into the registry database, where transplant centers worldwide can search for matches.
Who Can Register
You need to be between 18 and 40 years old to join the NMDP registry, though the program focuses its recruiting efforts on people ages 18 to 35. That’s because medical research consistently shows younger donors provide the greatest chance of transplant success, and doctors strongly prefer donors in that age range. You also need to be in generally good health and willing to donate to any patient who matches.
Several medical conditions will disqualify you from registering:
- HIV/AIDS
- Cancer, or cancer treatment (chemotherapy or radiation) within the past five years
- Autoimmune diseases that affect the whole body, such as lupus
- Severe arthritis, including rheumatoid arthritis
- Bleeding disorders like hemophilia or deep vein thrombosis
- Insulin-dependent diabetes
- Chronic hip, back, or spine pain requiring ongoing medication
- Chronic Lyme disease
If you have diabetes but manage it without insulin, you may still be eligible. The health questionnaire during registration screens for these conditions, and additional testing happens later if you’re identified as a potential match.
What Happens If You Match a Patient
Most people who register never get called. Finding a match depends heavily on how common or rare your HLA markers are. For patients of European descent, a well-matched donor can be found roughly 60 to 80 percent of the time. For patients from other ethnic backgrounds, the odds are significantly lower, which is why diverse donors are especially needed on the registry.
If you do match, NMDP will contact you, explain the process, and confirm you’re still willing and healthy enough to proceed. You’ll undergo additional blood testing and a physical exam. From that point, it typically takes several weeks before the actual donation happens, giving you time to prepare. The patient’s insurance covers all medical costs, and the registry covers your transportation and lodging if you need to travel to a donation center. You pay nothing.
Two Ways Donation Works
There are two collection methods, and the patient’s medical team decides which one is best for the patient. About 75 percent of the time, the method used is peripheral blood stem cell (PBSC) donation, which doesn’t involve surgery at all.
For PBSC donation, you receive daily injections of a medication for five days beforehand that encourages your body to push stem cells from your bone marrow into your bloodstream. On collection day, blood is drawn from one arm, run through a machine that filters out the stem cells, and returned to your other arm. The process takes four to eight hours. The most common discomfort is bone or muscle aches from the injections, plus the small pinch of placing an IV. Donors who’ve experienced both methods report that PBSC donation is less physically demanding, less time-consuming, and more convenient. The median recovery time is about one week.
For surgical marrow donation, you’re placed under general anesthesia while doctors use a needle to withdraw liquid marrow from the back of your pelvic bone. You won’t feel anything during the procedure. Afterward, you may be drowsy for up to 48 hours and experience some soreness at the collection site, along with possible headaches or muscle aches. These symptoms typically fade within 72 hours and respond well to over-the-counter pain relievers. The median time to full recovery is about 20 days, and your marrow naturally replenishes itself within a few weeks.
Regardless of the method, most donors return to work, school, and normal activities within one to seven days.
If You’re Outside the U.S.
The World Marrow Donor Association (WMDA) coordinates registries in over 50 countries, and all of them are interconnected. A patient in Germany can match with a donor in Brazil or Japan. If you’re outside the U.S., visit the WMDA website and use their “Find Your Registry” tool to locate the donor registry in your country. The registration process is similar everywhere: a health screening, a cheek swab or blood sample, and your HLA data entered into the global search network.
Why Staying on the Registry Matters
Joining the registry is a commitment that may never require anything of you, or it may one day mean everything to a stranger with leukemia, lymphoma, or another life-threatening blood disorder. Because HLA matching is so specific, some patients wait months or years for a compatible donor. Every new registrant, especially from underrepresented ethnic backgrounds, meaningfully improves those odds. If your health status or contact information changes after you register, update your profile so the registry can reach you when it counts.