There are several methods, here is one: http://www.marrow.org/Registry_Members/Donation/Donation_FAQs.aspx#process http://www.marrow.org/Registry_Members/Donat

There are several methods, here is one: http://www.marrow.org/Registry_Members/Donation/Donation_FAQs.aspx#process http://www.marrow.org/Registry_Members/Donation/Donation_FAQ... And here is another: http://en.wikipedia.org/wiki/Apheresis http://en.wikipedia.org/wiki/Apheresis The second one is the more likely one to be used, the other is quite rare. In this case it seems it is 'only' the second (which is still quite bit more time consuming than a normal blood donation in duration).