While personalized medicine has transformed healthcare over the last two decades, the blood donation process has remained basically unchanged. In this issue of TRANS-FUSION, the article by Kim et al 1 shows how discrete event simulation (DES) modeling 2 can be used to select the right donors and minimize deferrals, thus ensuring that the donor's experience is optimized to encourage repeat donation.Three important developments in blood banking preceded this study. First, until the last decade, it was very difficult to extract a large amount of data from donor records, as most were on paper.