I've heard a few numbers thrown around, 1 in 20,000 comes up often, but I haven't found any reputable sources to back that up. According to the National Marrow

I've heard a few numbers thrown around, 1 in 20,000 comes up often, but I haven't found any reputable sources to back that up. According to the National Marrow Donor Program: "On average, one in every 540 members of Be The Match Registry in the United States will go on to donate marrow to a patient." http://marrow.org/Registry_Members/Donation/Donation_FAQs.aspx#likely http://marrow.org/Registry_Members/Donation/Donation_FAQs.as... I can say from personal experience that I've been a registered donor for 8 years, and only just yesterday did I receive an e-mail saying that I may be a possible match for a patient. The process going forward is fairly long with tests along the way to be certain (http://marrow.org/Registry_Members/Donation/Steps_of_Donation.aspx#step1 http://marrow.org/Registry_Members/Donation/Steps_of_Donatio...). I was told it could be up to 2 months before doctors decide if I move on to the next stage of donation. If the doctors decide I'm the best match, it could be another 6 months before the actual donation.