Skip Navigation

What is HLA matching?

HLA matching is used to match patients and donors for blood or marrow transplants. If 2 people share the same HLA type, they are considered a 'match'. It's much more complicated than blood typing.

How does matching happen?

  1. You and potential donors will have blood drawn or will have the inside of your cheek swabbed.
  2. The blood or cheek swab is tested in a lab to figure out your HLA type.
  3. Your HLA type will be compared to potential donors to see if there is a match. Your doctor will decide which donor has the best HLA match for you.

What are my chances of having a match?

There are many HLA markers. Each HLA marker has a name. The names are letters or combinations of letters and numbers.

Sometimes, it’s hard to find a match because some HLA types are less common. HLA types are inherited so siblings can sometimes be a match for each other. Each of your brothers and sisters who has the same mom and dad as you has a 1 in 4 chance (25%) of being a complete, or full, match. You’re more likely to match someone with a similar ethnic background or ancestry.

Where can I get my HLA tested?

You can have HLA typing done at your:

  • Transplant center
  • Cancer clinic or cancer center

If you haven't been to a transplant center yet, your doctor can test your HLA type for free through our HLA Today program.

Contact our Patient Support Center with any questions:

If you are a hematologist or oncologist who would like to learn more about our HLA Today program, visit or email us at

Why is finding the best donor or cord blood unit (CBU) important?

Your doctor wants to find the best possible donor or CBU for you. Usually, it’s a donor or CBU whose HLA are very closely matched to yours.

A close match is important because it:

  • Improves the chances for a successful transplant.
  • Helps your donor cells engraft (grow and make new blood cells in your body).
  • Reduces the risk of complications like graft-versus-host disease (GVHD). GVHD happens when the immune cells from the donated cells (the graft) attack the recipient’s cells (the host).

There are times when a closely matched donor isn’t the best option. For some patients, a donor who matches exactly half of their HLA is best. This is called a haploidentical (or half-matched) transplant.