The majority of people on our register never donate. Once you are on the register you have a 1 in 800 chance of being asked to donate in the next five years.

But your chance of being chosen to donate depends on your age and sex. A young man aged 16–30 has a 1 in 200 chance of being chosen to donate in the next five years.

We’ll only ask you to donate if you have a similar tissue type to someone in desperate need of a transplant.

If you’re a match and refuse, it could be devastating news for someone with a life-threatening illness. That’s why we ask you to be fully committed when you sign up.

You can donate your stem cells in two ways – through peripheral blood stem cell (PBSC) collection or bone marrow donation. Around 90% of people donate via PBSC collection. However, in some situations and for some conditions, a patient will need stem cells from bone marrow.

If you join our register, you must be willing to donate in either way.

On each of the four days before you donate, you will receive injections of granulocyte colony-stimulating factor (G-CSF). This is a naturally occurring hormone that increases the number of stem cells your body produces.

You’ll then come to one of our collection centres (in London, Oxford, Sheffield or Manchester), where a doctor will insert a tiny tube in your arm, draw out your blood, and pass it through a machine to collect the stem cells.

Donating only takes 4-5 hours for most people. At the end, a nurse will check how many stem cells you’ve donated. There is a chance that you’ll be asked to come back the next day to donate more.

You won’t need a general anaesthetic or to stay in hospital overnight.

Side effects can include flu-like symptoms and aching. But they’re usually mild and last just a couple of days. You’ll receive lots of information and support for how to deal with them.

If you need to give cells from your bone marrow (found inside your large bones), doctors will give you a general anaesthetic and draw the cells from your pelvis using a sterile needle and syringe.

You will need to stay in hospital for two nights if you donate bone marrow.

You’ll probably feel tired and have a little bruising after, but this generally passes within a week or so. You’ll receive lots of information and support for how to deal with them.

They could be anywhere in the world, but they are more likely to be in the UK.

We link with registers worldwide to find matches for people in the UK and provide stem cells for people in need abroad.

Yes. We can search registers in countries around the world to find a match for someone in the UK. That’s over 38 million potential donors.

The majority of our donors and recipients never meet.

For two years after the procedure, donors and recipients can only contact each other through messages sent via our team. After two years, and only if the recipient instigates it, they can exchange contact details.

Some other registers and transplant centres don’t allow contact at all, or have different guidelines. So if they’re involved in a transplant, donors and recipients may have to follow their rules.

We have strict rules so there can be no suggestion of a potential donor being coerced or induced to donate for financial or other reward. We also strongly believe in the importance of protecting the privacy of both the recipient and the donor.

No. It's highly unlikely that two friends will share the same genetic profile. The best hope for your friend is to find a donor on our register, or on another international register.

But if you’re 16–30 years old and in good health, you could join our register and potentially save someone’s life.

You can join our register by completing this form. Please mention that you’ve been tissue typed before.

We’d appreciate it if you could forward us a copy of your HLA tissue typing results by email to donor.support@anthonynolan.org .You should be able to get the tissue typing report from the hospital that did your testing.

If you have any questions, please do give us a call on 0303 303 0303.

If you donate, you'll be asked if you want to stay on our register and potentially donate again.

Although it’s unusual, some of our donors have donated more than once. We allow donors to give stem cells a maximum of four times.

Please visit the NHS Blood & Transplant website for more information.

Putting people on the register who are statistically unlikely to be selected is not only expensive but also diverts our scientists away from processing the samples of younger volunteers who are more likely to be selected. We will save more lives by ensuring that we have a register of people who are most likely to be selected by transplant clinicians. Also we are proactively recruiting younger donors from minority ethnic backgrounds to increase the diversity of the register.

Yes, there are. You have to be between 16 and 30 and in good health. Take a look at our join the register page.

The British Bone Marrow Registry (operated by NHS Blood & Transplant) accepts donors between the ages of 17-40. You must be a blood donor to join the BBMR, as an extra sample of blood is taken when you donate. The BBMR is in particular need of donors from minority ethnic backgrounds; if you're interested, please ask at your blood donation session BEFORE you donate blood. Go to blood.co.uk for more information on your nearest blood donation session and how to sign up as a blood donor.