Safety of blood and blood products is a major problem all over the world. Screening for the markers of infectious diseases is an incomplete solution. One of the most important steps in improving the safety of blood and blood products is donor selection. In this study, causes of donor deferral were evaluated retrospectively in the blood center of a childrens hospital. Analysis of the deferrals showed that the most commonly defined causes were recent sexual exposure in high-risk activity, recent ingestion of medication., low hemoglobin level, abnormal blood pressure, being underweight, tattoos, piercing or acupuncture. in. the preceding 6 months, recent history of injection and presenting for a subsequent donation too soon, elevation, of Presence of the markers of the infectious diseases.