Joining a bone marrow registry takes about 10 minutes online and one cheek swab at home. You order a free kit, swab the inside of your cheeks, mail it back, and your tissue type gets added to a global pool of around 43 million potential donors. From that point on, you could be contacted as a match for someone who needs a transplant.
The Registration Steps
The process is the same across major registries like NMDP (formerly known as Be The Match) and DKMS. You visit their website, answer a short health questionnaire, and request a swab kit. The kit arrives in the mail within a few days. Inside, you’ll find cotton swabs and a prepaid return envelope.
You rub the swabs along the inside of your cheeks for about 30 seconds each. This collects enough cells to determine your HLA type, which is the set of proteins on your cells that a patient’s body uses to recognize tissue as “self” or “foreign.” Your HLA profile is what determines whether you’re a match for someone. Once the lab processes your swabs, your profile is added to a searchable global database. There’s nothing else to do until you’re contacted as a potential match, which may be months, years, or never.
Who Can Join
Most registries accept donors between the ages of 18 and 60, though the preferred range is 18 to 35. Younger donors produce more stem cells, and transplant centers request them more often because the cells tend to perform better for the patient. Bone marrow ages along with the rest of the body. Structures at the ends of chromosomes called telomeres shorten over time, limiting how many times cells can reproduce. Marrow from an older donor transplanted into a younger patient may not sustain itself as long. The World Marrow Donor Association sets the upper limit at 60.
You also need to be in generally good health. Conditions that disqualify you include HIV, cancer (or cancer treatment within the past five years), autoimmune diseases that affect your whole body, bleeding disorders like hemophilia, diabetes, severe arthritis such as rheumatoid arthritis, chronic Lyme disease, and chronic back or hip pain that requires ongoing treatment. The health questionnaire during registration screens for these. If you’re unsure whether a specific condition disqualifies you, the registry’s medical team reviews borderline cases individually.
Why Ethnicity Matters for Matching
HLA types are inherited, so people with similar ancestry are far more likely to match each other. This creates a significant gap in match rates across ethnic groups. About 79% of white patients find a matched donor through the registry. For Hispanic and Asian patients, that number drops to around 47-48%. For Black patients, it falls to 29%.
These gaps exist because minority groups are underrepresented in registries worldwide. If you belong to an underrepresented ethnic group, or if you have a mixed ethnic background, your registration carries outsized importance. You may be the only viable match for someone who has no other options. The global registry network spans over 130 organizations in 57 countries, and registries are encouraged to search internationally to maximize the chance of finding a donor. But that only works if the right profiles are in the system to begin with.
What Happens If You’re Called as a Match
The odds of being contacted vary. Most registered donors are never called. If you are identified as a potential match, you’ll go through additional blood tests to confirm compatibility, followed by a physical exam. The registry covers all medical costs, travel, and related expenses. You won’t pay anything out of pocket, and you’re covered by a donor life, disability, and medical insurance policy for any complications directly related to your donation.
There are two ways donation actually works, and the transplant team chooses based on what the patient needs.
The more common method is peripheral blood stem cell donation. For five days before the procedure, you receive daily injections of a medication that pushes stem cells out of your bone marrow and into your bloodstream. On donation day, blood is drawn from one arm, passed through a machine that filters out stem cells, and returned through your other arm. This takes four to six hours and is done as an outpatient procedure. Recovery is typically a few days, though some donors feel bone aches from the injections for a short period.
The second method is a surgical bone marrow harvest. Under general anesthesia, doctors use a needle to withdraw liquid marrow from the back of your pelvic bone. The procedure takes one to two hours. You can generally return to normal activities within a couple of days, but it may take a couple of weeks to feel fully recovered. Soreness at the collection site is the most common complaint.
Where to Register
In the United States, the largest registry is NMDP, which manages the national donor database and connects to the global search network through the World Marrow Donor Association. DKMS is another major registry that operates internationally. Both accept online registrations and mail swab kits for free. Your profile becomes searchable by transplant centers worldwide regardless of which registry you join, since they all feed into the same global matching system of nearly 43 million donors and cord blood units.
Registration is a commitment that lasts until you age out at 61. If you move or change your phone number, updating your contact information matters. The worst outcome for a patient is finding a perfect match who can’t be reached. Once you’re on the registry, staying reachable is the most important thing you can do.