The blood types listed below are compatible: Blood type A donors can donate to recipients with blood types A and AB. Blood type B donors can donate to recipients with blood types B and AB. Donors of blood type AB can only donate to receivers of blood type AB. They will not be able to donate to recipients who have blood type A or B. Blood type is the single most important factor in determining whether someone will respond to a blood transfusion. The three main types are A, B, and O. Recipients receive an infusion of blood components from their own blood type when they undergo surgery or other procedures that may lead to bleeding or need replacement of lost blood. Providing a recipient with blood of the same type as theirs saves the transplant patient from requiring additional donations. A donor can give blood type A if they are a man or woman and age 18 or older. In general, people who have blood type A tend to make better donors because it takes them longer to bleed out. However, individuals who are younger or who have blood type O can also donate type A blood. People who have blood type A must be negative for all other antigens before they can be eligible to donate. That means they cannot have any of the other blood groups present. If you have blood type A and are already aware that you have it, then you are eligible to donate.