Registering to be a bone marrow donor takes about 10 minutes online and costs nothing. You order a free cheek swab kit, mail it back, and your tissue type gets added to a national registry where you could be matched with a patient who needs a transplant to survive. Here’s exactly how the process works and what to expect.
Who Can Register
You need to be between 18 and 35 years old to join the registry through NMDP (formerly known as Be The Match), the largest marrow donor program in the United States. Once registered, you stay on the registry until you either opt out or turn 61.
Several medical conditions will disqualify you. These include HIV, hepatitis B or C, cancer (or cancer treatment within the past five years), insulin-dependent diabetes, heart disease, kidney disease, bleeding disorders like hemophilia, autoimmune diseases that affect your whole body (such as rheumatoid arthritis), and brain injuries. The screening questions during online registration will help determine whether you’re eligible before a kit is mailed to you.
Step-by-Step Registration
Start by visiting the NMDP website and answering a few eligibility questions. If you qualify, you’ll provide a mailing address, and a free swab kit typically arrives within 3 to 7 days.
Inside the kit you’ll find two sterile cheek swabs, barcode labels, detailed instructions, and a prepaid return envelope. The process is simple but has a few rules for getting a clean sample:
- Don’t eat or drink for 30 minutes before swabbing.
- Wash your hands thoroughly.
- Swab firmly inside one cheek for 10 seconds, then use the second swab on the other cheek.
- Let both swabs air dry for 2 to 5 minutes before packaging them.
- Place the swabs in the return packaging with swab tips pointing left and the barcode facing up.
Seal the prepaid envelope and drop it in the mail. The lab will process your samples to determine your tissue type and add your profile to the registry.
How Matching Works
Your cheek swab reveals your tissue type, specifically a set of proteins on your cells called HLA markers. These markers are inherited from your parents, which is why matches are most likely to come from someone with a similar ethnic background. Transplant teams test for eight key markers across four genes. An ideal donor matches on all eight. When a perfect 8-out-of-8 match isn’t available, a 7-out-of-8 match can still be considered, though outcomes are better with a full match.
This is where the registry’s biggest challenge becomes clear. Patients from underrepresented ethnic groups have a much harder time finding matches. About 71% of Black patients and 71% of multiracial individuals cannot find a perfectly matched donor in the worldwide registry. For Latino and Hispanic patients, that figure is 52%, and for Asian Americans, 53%. Every new registrant from these communities meaningfully improves the odds for patients waiting for a transplant.
What Happens If You Match
Most registered donors are never called. But if you do come up as a potential match, the registry will contact you for additional blood testing to confirm compatibility. You can change your mind at any point in the process, though backing out after a patient has begun preparation for transplant can be life-threatening for them.
If you move forward, the donation method depends on what the recipient’s medical team determines is best. About 90% of donors provide cells through a process called peripheral blood stem cell donation, which is nonsurgical. You receive injections over several days beforehand that push blood-forming cells from your bone marrow into your bloodstream, and then your blood is drawn through a needle, filtered through a machine that collects the stem cells, and returned to your body. The remaining 10% of donors undergo a surgical procedure where cells are collected directly from the back of the hip bone under anesthesia.
Costs and Logistics
Registration is free. If you’re called to donate, the recipient’s insurance typically covers all medical costs associated with the procedure, including HLA testing, the donation itself, and related expenses. You won’t receive a bill for any part of the medical process. Travel and lodging costs for getting to the donation center are also generally handled through the registry program, not out of your pocket.