The conventional techniques used to prepare leukocyte-poor red cell concentrates are described. These techniques conveniently group by their primary processing modalities which are centrifugation, freeze thawing, cell washing, and filtration. Each of these procedures has unique logistical requirements. The complexity, need of dedicated capital equipment, and stringent quality assurance requirements make the use of some of these techniques impractical for the hospital blood bank laboratory. The majority of patients benefit from the receipt of leukocyte-poor blood products prepared by an "in-line" microaggregate filtration technique. Those patients with symptoms which prove to be refractory to microaggregate-filtered blood products and those who require highly purified red cell concentrates to forestall sensitization to transplantation antigens should receive blood prepared either by the cryopreservation/deglycerolization technique or by cotton wool filtration.