Most healthy adults between the ages of 18 and 44 can donate bone marrow or blood stem cells. The registry actively recruits donors ages 18 to 35 because younger donors produce better outcomes for patients, but you can remain on the registry and donate through age 60. Beyond age and general health, eligibility depends on a set of medical guidelines that screen out conditions posing risks to the donor or the recipient.
Basic Eligibility Requirements
To join the bone marrow registry, you need to be at least 18 years old and in generally good health. The National Marrow Donor Program focuses its recruiting efforts on people ages 18 to 35 because transplant doctors consistently see better patient outcomes with younger donors. You won’t be removed from the registry at 36, but the sweet spot for recruitment sits in that younger range.
Pregnancy is a temporary deferral. You cannot donate during pregnancy or for six months after delivery or termination. Breastfeeding also defers eligibility until you’ve stopped.
Conditions That Disqualify You
A number of chronic and serious health conditions permanently prevent donation. The guidelines exist to protect both you and the patient receiving the transplant. The major disqualifying categories include:
- Cancer: Any history of cancer disqualifies you, regardless of how long ago you were treated or whether you’ve fully recovered.
- HIV: A diagnosis permanently prevents donation.
- Heart disease: This includes a prior heart attack, bypass surgery, angioplasty, valve replacement, or a pacemaker.
- Stroke or brain injury: Any history of stroke, mini-stroke (TIA), bleeding in the brain, or brain surgery disqualifies you, even if you’ve fully recovered.
- Autoimmune disorders: Multiple sclerosis, lupus, chronic fatigue syndrome, and fibromyalgia all prevent donation. Severe forms of arthritis, including rheumatoid and psoriatic arthritis, also disqualify you.
- Serious liver disease: Hepatitis B, hepatitis C, and Wilson disease are all permanent deferrals.
- Serious kidney disease: Polycystic kidney disease (if you’re over 40), chronic glomerulonephritis at any age, or having had a kidney removed due to disease.
- Insulin-dependent diabetes: If you require insulin or have diabetes-related complications affecting your kidneys, heart, or eyes, you cannot donate.
Some conditions are less obvious. Chronic back pain that requires daily medication, physical therapy, or chiropractic treatment will disqualify you. Asthma that requires daily oral steroids (not an inhaler) is also a deferral. Chronic Lyme disease prevents donation as well.
How Matching Works
Bone marrow matching isn’t based on blood type. It’s based on a set of proteins on the surface of your cells called HLA markers. These markers are inherited from your parents, which is why a sibling is often the first place doctors look for a match. A sibling donor needs to match on at least 6 of 6 key markers. When no family match exists, the search moves to the public registry.
For an unrelated donor, the standard is stricter: an 8 out of 8 match across four HLA marker types. When a perfect 8/8 match isn’t available, a 7/8 match (one marker off) can still be acceptable, though transplant outcomes are somewhat better with a full match. Half-matched (haploidentical) transplants from a parent or child are also possible in some cases, requiring at least a 4 out of 8 match.
Umbilical cord blood transplants have more flexible matching requirements, needing only a 4 out of 6 match, which makes cord blood a useful backup option when no well-matched adult donor exists.
Why Ethnicity Matters for the Registry
Because HLA markers are inherited, your best chance of matching is with someone who shares your ethnic background. This creates a significant disparity. White patients find a same-ethnicity donor roughly 91 to 95% of the time. For ethnic minorities collectively, that number drops to around 33 to 47%. African American, Hispanic, Asian, American Indian, and mixed-race patients all face substantially lower odds of finding a well-matched donor on the registry.
This gap exists because minority populations are underrepresented on donor registries and because some ethnic groups have more diverse HLA profiles, making any single match harder to find. If you belong to an underrepresented group, joining the registry has an outsized impact. One registration could be the only potential match for a patient who has no other options.
What Donation Actually Involves
There are two methods of donation, and the medical team typically chooses which one based on the patient’s needs. More than 85% of donations today use a nonsurgical method called peripheral blood stem cell (PBSC) collection. The remaining cases involve a traditional surgical bone marrow harvest.
PBSC Donation
For PBSC donation, you receive daily injections of a medication for about five days beforehand. This drug stimulates your body to push extra blood-forming stem cells out of your bone marrow and into your bloodstream. On collection day, blood is drawn from one arm through a needle, run through a machine that filters out the stem cells, and returned to your other arm. The most discomfort most donors feel is the pinch of the IV and some bone or muscle aches from the injections, which typically fade within 72 hours. Median recovery time is about one week.
Surgical Marrow Donation
Surgical donation takes place in an operating room under general or regional anesthesia. A surgeon uses a needle to withdraw liquid marrow from the back of your pelvic bone. You may stay in the hospital for a few hours or overnight. Expect grogginess for up to 48 hours after anesthesia. The median time to full recovery is about 20 days, as your bone marrow replenishes itself naturally within a few weeks.
For both methods, most donors return to work or school within one to seven days.
Costs and Coverage for Donors
Donating bone marrow costs you nothing out of pocket. If you need to travel, your travel expenses and other donation-related costs are covered. You’re also covered by a life, disability, and medical insurance policy for any complications directly related to the donation itself. The patient’s insurance or transplant center bears the medical costs, not you.