One of the most controversial topics in our field in recent years has been the question of whether or not the transfusion of stored red cells has adverse effects on patients. It has been proposed that the numerous changes which are known to occur to red cells during storage impair their function when transfused and, furthermore, may be actively deleterious. A large number of retrospective clinical studies, and a few prospective studies, have been carried out to address this issue, but the results have not been conclusive. Within the past two years, several randomized clinical trials addressing the effect of red cell storage on patient outcomes have been initiated. In this session consisting of three lectures, the speakers will summarize our current understanding of this issue based on the results of published clinical studies, and describe two randomized, controlled clinical trials that have been designed to provide an answer to this question.