Bone marrow can be found in nearly every bone in your body, donated through national registries and transplant centers, or purchased from butchers and specialty retailers for cooking. The answer depends on whether you’re asking about anatomy, medical procedures, or food, so let’s cover all three.
Where Bone Marrow Exists in Your Body
Every bone in your skeleton contains marrow, but not all marrow is the same. Red bone marrow is the active, blood-producing type. It manufactures red blood cells, white blood cells, and platelets. Yellow bone marrow is mostly fat and serves as an energy reserve.
At birth, your entire skeleton is filled with red marrow. Over the course of childhood and adolescence, a gradual conversion takes place: red marrow is steadily replaced by yellow marrow, starting in your hands and feet and working inward toward your torso. By age 25, this process is complete, and red marrow settles into its adult pattern. It concentrates in flat bones like the pelvis, sternum (breastbone), skull, shoulder blades, and the bodies of your vertebrae. The ends of your upper arm bones and thighbones also retain some red marrow. Your fingers, toes, and the shafts of long bones contain only yellow marrow by adulthood.
As you age further, yellow marrow continues to slowly expand, eventually becoming dominant even in the pelvis and spine. This is one reason older adults produce blood cells less efficiently than younger people.
Where Doctors Extract Bone Marrow
When bone marrow needs to be collected for a biopsy or a donation, the go-to site is the back of the hip bone, specifically the top ridge of the posterior iliac crest. This spot is chosen because it’s a large, accessible bone with a rich supply of marrow and relatively few nerves nearby. Occasionally, the front of the hip is used instead. In rare cases, marrow aspiration (but not a full biopsy) can be taken from the breastbone. For infants under about 18 months, the lower leg bone is sometimes used.
How to Donate Bone Marrow
The primary pathway in the United States is through the National Marrow Donor Program (NMDP), which maintains a registry of potential donors who can be matched to patients needing a transplant. You can join the registry online or in person at a donor drive. The process involves filling out a health history questionnaire, providing contact information, signing an agreement, and swabbing the inside of your cheek so your tissue type can be analyzed and stored.
You need to be in good health and willing to donate to any patient in need. The NMDP focuses its recruitment on people ages 18 to 35 because younger donors consistently produce better outcomes for patients and the greatest chance of transplant success. People outside that range can still register, but younger donors are prioritized for outreach.
What Donation Actually Looks Like
If you’re matched with a patient, the collection method depends on what the patient’s medical team recommends. Traditional bone marrow harvest involves a surgical procedure where marrow is drawn from the back of your hip bone with a needle under anesthesia. The other method, peripheral blood stem cell (PBSC) collection, skips surgery entirely. You receive injections over several days that coax stem cells out of your marrow and into your bloodstream, then the cells are filtered out through a process similar to donating blood plasma.
PBSC is now far more common than surgical harvest. In 2024, 86% of unrelated donor transplants used peripheral blood stem cells, with only 10% using traditional bone marrow collection. For related donors, PBSC still dominated at 77%, though bone marrow harvest was used more often (23%) than in unrelated donations. Umbilical cord blood, collected after a baby is born, accounts for a small share, primarily in unrelated transplants.
Recovery After Donating
If you undergo the surgical harvest, expect to take several days off work. You’ll feel pain at the needle site when bending or walking, which tends to ease within the first few days. Most soreness and fatigue resolve within a few weeks as your marrow replenishes itself. The total recovery process typically takes two to six weeks, though some discomfort can linger for up to 12 weeks in rare cases. PBSC donors generally recover faster, with the most common side effects being bone aches from the pre-collection injections, which fade once the donation is complete.
Self-Donated vs. Donor Marrow for Treatment
In transplant medicine, marrow can come from you (autologous) or from someone else (allogeneic). Your own marrow carries no risk of immune rejection, which is a significant advantage. The downside is that it takes weeks to harvest, grow, and prepare your cells in a lab, and if you have a systemic disease, your own marrow cells may be compromised by that same disease. In conditions like lupus, for example, a patient’s own stem cells can have impaired immune function due to the underlying genetic abnormality, making self-donation a poor option.
Donor marrow offers more flexibility. Doctors can select donors carefully, tap into multiple tissue sources, and have cells available on a faster timeline. The tradeoff is that donor cells can sometimes trigger an immune response in the recipient, particularly with repeated treatments. In one study, a second injection of donor-derived cells into joints caused a significant adverse reaction, suggesting the body had developed immune memory against the foreign cells. For certain conditions like heart disease, donor cells have shown better results than self-derived cells in improving heart function and exercise capacity.
Where to Buy Bone Marrow for Cooking
If your search is about food, bone marrow is widely available and increasingly popular. Beef marrow bones are the most common type sold for cooking, typically cut from the front leg of the cow where the bones are large and packed with rich, fatty marrow. You can find them at butcher shops, grocery store meat counters, farmers’ markets, and online retailers that ship frozen cuts directly to your door. Packs are commonly sold in 2 to 2.5 pound portions. Veal, lamb, and bison marrow bones are also available at specialty butchers, though beef is the standard.
For preparation, many chefs recommend soaking split bones in salted water overnight before cooking. The salt draws blood out of the bone, resulting in firmer marrow that holds its shape better during roasting. Not everyone agrees this step is essential (some argue seasoning matters more than soaking), but it does produce a cleaner-looking finished product. Beyond roasting and spreading on toast, marrow bones are a foundation for homemade beef stock and bone broth, where long simmering extracts both flavor and gelatin from the bones.