BACKGROUND Receiving a temporary deferral has been shown to negatively affect donor retention. One contributing factor for low donor return may be poor understanding of why the deferral has occurred. The aim of this study was to determine whether new educational materials-a brochure, guided conversation, and follow-up email-increased deferred donors' knowledge about their donation eligibility, satisfaction with the deferral process,
intention to return, and odds of rebooking another appointment. STUDY DESIGN AND METHODS A three-arm cluster randomised controlled trial was conducted to evaluate the impact of the educational materials compared to business as usual deferral procedures: (a) In-center brochure and follow-up email; (b) Email only; (c) Control. A survey was administered to a random sample of trial participants (n = 847). RESULTS Compared with the control condition, donors in the in-center brochure and email condition were more knowledgeable about the end date of their deferral, and reported higher satisfaction with the deferral information provided, and had fewer questions and/or concerns about the deferral. Similar findings were observed when comparing the email only condition to the in-center brochure and email condition. No differences were found in intention to return. Donors in the in-center brochure plus email condition had increased odds (OR:1.385) of rebooking their next appointment compared to the combined email only and control conditions. CONCLUSIONS The application of a deferral is often misunderstood by donors. Providing educational materials to donors can increase their understanding and may lead to increased retention of donors through rebooking of subsequent donations.