Blood conservation has evolved into an important issue in hospital-based medicine. Increased awareness of and worry about transfusion-associated diseases have prompted a focus on this important area. New technologies, including continuous intraarterial monitoring devices, microchemical technologies, new drug development (recombinant human erythropaietin and aprotinin) and intraoperative salvage techniques have made the concept of clinically important blood conservation possible. In this article, the authors review clinically important areas regarding blood conservation, which are subsequently detailed in this issue of AACN Clinical issues. Emphasis is placed on the need for blood conservation in acute and critical care practice and the technologies available to achieve this goal.