There are four basic blood types: type O, A, B and AB. There are two Rh factor categories, which are Rh positive (Rh +) or Rh negative (Rh-).When you complete your first donation, BloodSource will mail you a blood donor card in about four weeks that indicates your blood type and Rh factor.

BloodSource needs regular donations from donors of all blood types, even the most common. Because a higher percentage of patients need the common types, the demand for donors is constant.