The most important studies published to date concerning the methods of preparation and the clinical utility of young red blood cells are reviewed 20 years after the first discoveries were made in this field. The results of each of the seven methods utilized (cells separators, cell washers, manual methods, etc.) are analyzed and the author's opinion is given concerning the results of in vitro and in vivo application. With few exceptions, the reviewed studies were done using small numbers of individuals. The majority of the studies confirm that it is possible to obtain YRBC enriched units. They also agree that YRBC have a higher survival rate in vivo than do normal RBC. In contrast, many of the wider-based studies did not show positive results when YRBC were used in patients or the results were too weak to justify the large amount of time and money these methods demand. Based on the review of all of the investigations published to date, there is little evidence to sustain the assumption of the clinical utility of YRBC used for multitransfused patients.