To donate bone marrow, you generally need to be between 18 and 60 years old, in good overall health, willing to undergo HLA typing, and able to pass a comprehensive medical screening. The single most important requirement is having a close human leukocyte antigen (HLA) match with the recipient — ideally a 10/10 match at the key HLA loci. Without that match, nothing else matters.
If you’re researching bone marrow transplant donor requirements because you’re thinking about joining a registry, have been asked to donate for a family member, or are a patient trying to understand the process, this guide covers every step — from who qualifies to what actually disqualifies you, and what the donation process looks like in practice.
The #1 Requirement: HLA Matching
HLA (human leukocyte antigen) proteins sit on the surface of most cells in your body. They’re how your immune system tells “self” from “foreign.” In bone marrow transplantation, the closer the HLA match between donor and recipient, the lower the risk of graft-versus-host disease (GVHD) — a potentially life-threatening complication where donated cells attack the recipient’s tissues.
Transplant teams typically look at 10 HLA markers (5 loci, each with 2 alleles). Here’s how match quality breaks down:
| HLA Match Level | Match Type | GVHD Risk | Typical Source |
|---|---|---|---|
| 10/10 | Perfect match | Lowest | Sibling or unrelated donor |
| 9/10 | Single-antigen mismatch | Moderate | Unrelated donor |
| Haploidentical (5/10) | Half-match | Higher (mitigated with newer protocols) | Parent, child, or sibling |
| Cord blood | 4–6/6 (fewer loci tested) | Variable | Umbilical cord blood banks |
A sibling has roughly a 25% chance of being a perfect HLA match. For patients without a matched sibling, the search moves to registries like the National Marrow Donor Program (Be The Match), which has over 40 million registered donors worldwide. Even so, certain ethnic groups — particularly Black, Hispanic, Native American, and mixed-race patients — face significantly lower odds of finding a 10/10 unrelated match, sometimes below 25%.
Age and General Health Requirements
Most registries accept donors between ages 18 and 40 for new registration, though donors already on the registry can be called upon up to age 60. Younger donors (18–35) are statistically preferred because their stem cells tend to engraft faster and produce better outcomes for recipients.
Beyond age, donors must meet general health criteria:
- BMI: Most centers require a BMI under 40. Some set the cutoff at 35.
- No active cancer or history of blood-related cancers (ever).
- No HIV, hepatitis B, or hepatitis C infection.
- No autoimmune diseases requiring systemic immunosuppressive therapy (lupus, rheumatoid arthritis on biologics, etc.).
- No severe heart, lung, liver, or kidney disease.
- Not currently pregnant.
Conditions like well-controlled asthma, treated hypothyroidism, or mild seasonal allergies usually do not disqualify you.
The Donor Screening Process: Step by Step
Step 1: HLA Typing
This starts with a simple cheek swab or blood draw. DNA is extracted and analyzed at high resolution to map your HLA alleles. Results are entered into the registry database. You could wait years — or never be called.
Step 2: Confirmatory Testing
If you’re identified as a potential match, the transplant center orders a second, more detailed HLA test to verify the match. This is called confirmatory typing (CT).
Step 3: Comprehensive Medical Evaluation
Once confirmed, you undergo a thorough workup that includes:
- Complete blood count (CBC) — checking hemoglobin, white blood cell count, and platelet levels
- Comprehensive metabolic panel — liver and kidney function
- Infectious disease screening — HIV, hepatitis B & C, CMV, syphilis, West Nile virus, HTLV
- Chest X-ray and EKG — baseline cardiac and pulmonary function
- Pregnancy test (for applicable donors)
- Detailed medical history and physical exam
This evaluation protects both you and the recipient. The entire process from initial call to donation typically takes 4 to 6 weeks.
Step 4: The Actual Donation
There are two methods, and the transplant team — not the donor — usually decides which is needed:
Peripheral blood stem cell (PBSC) collection (~80% of donations): You receive injections of filgrastim (G-CSF) for 5 days to mobilize stem cells from your marrow into your bloodstream. On day 5 (sometimes day 4 and 5), blood is drawn from one arm, passed through an apheresis machine that collects stem cells, and returned through the other arm. The process takes 4–8 hours.
Bone marrow harvest (~20% of donations): Under general anesthesia, doctors use needles to withdraw liquid marrow from the back of your pelvic bones. They typically collect about 1–2 liters of marrow-blood mixture (your body replaces it within 4–6 weeks). You’ll be sore for a few days to a couple of weeks.
Common Disqualifying Conditions
People are often surprised by what does and doesn’t disqualify them. Here’s a quick reference:
| Usually Disqualifying | Usually NOT Disqualifying |
|---|---|
| History of any blood cancer (leukemia, lymphoma, myeloma) | History of solid tumors treated and in remission >5 years |
| HIV positive | Controlled hypertension on medication |
| Active hepatitis B or C | Mild asthma |
| Severe autoimmune disease on immunosuppressants | Treated hypothyroidism |
| BMI over 40 | History of depression (stable, treated) |
| Chronic kidney or liver disease | Seasonal allergies |
| Type 1 diabetes (at most centers) | Well-controlled Type 2 diabetes (case-by-case) |
When in doubt, register anyway. The medical team will make the final determination if you’re ever called as a match.
Key Takeaways
- HLA matching is everything. A 10/10 match dramatically reduces complications. Siblings have a 25% chance; unrelated donors are found through registries.
- Joining a registry is easy and free. A cheek swab is all it takes initially. You can register at BeTheMatch.org in the U.S. or equivalent programs in other countries.
- Age 18–40 is ideal. Younger donors yield better recipient outcomes, which is why registries prioritize this age range for enrollment.
- Donation is safe. Serious complications for donors are rare — occurring in less than 1% of cases. Most side effects (bone pain, fatigue, headache) resolve within 1–2 weeks.
- Ethnic diversity in registries is critically needed. Patients from underrepresented backgrounds face the hardest time finding a match.
Frequently Asked Questions
Does donating bone marrow hurt?
With PBSC donation (the more common method), most donors report mild to moderate bone aches from the filgrastim injections — similar to flu-like body soreness. Bone marrow harvest is done under anesthesia, so you won’t feel the procedure itself, but you’ll have soreness at the hip for about 1–2 weeks afterward. Most donors return to work within 1–3 days (PBSC) or 1–7 days (marrow harvest).
Can I donate if I have a tattoo or piercing?
Yes, in most cases. If your tattoo was done at a licensed facility, there’s typically no deferral period. Some centers may ask you to wait 4–12 months if the tattoo was done in an unregulated setting, primarily to rule out bloodborne infections.
What if I’m on the registry and change my mind?
You can withdraw at any time, but transplant centers strongly urge donors not to back out once the recipient has begun conditioning therapy (the high-dose chemotherapy or radiation that destroys their existing marrow). At that point, the recipient literally cannot survive without the transplant. Backing out after conditioning has begun can be fatal for the patient.
How long does the whole process take?
From the initial “you’re a match” phone call to the actual donation day: approximately 4 to 6 weeks. The donation itself takes either one day (bone marrow harvest) or 1–2 days (apheresis for PBSC). Including recovery, plan for about one week of disruption to your normal routine.
Can someone over 60 still donate?
Registries generally don’t accept new registrants over 40, and donors over 60 are removed from most registries. However, if you’re donating directly to a family member (a directed donation), there is no strict age cutoff — the transplant team will evaluate you on a case-by-case basis based on your overall health.
