Background and objectives: Previous studies observed a transient increase in well-being in about one-third of regular donors after blood donation. In addition, personal contact with donors after donation seems to increase return rates. We were interested whether changes in well-being and/or personal contact after the first donation impact return rates of first-time donors (FTDs). Materials and methods: First-time donors were randomized to a questionnaire group (QG), in which questionnaires assessing the well-being had to be filled in, or a control group (CG), which was not contacted with a questionnaire. The QG had to complete the same questionnaire three times at the day of the first donation and then four times over an 8-week period with reminding calls by the study coordinator. Return rates of participants were followed for 12 months. Results: A total of 102 FTDs participated in the QG and 115 in the CG. Changes in well-being after the first donation had minimal impact on the return rates. In contrast, contacting FTDs after their first donation had a significant impact on the return rate of male donors (89!2% in the QG vs. 58!3% in the CG; P = 0.001). Females showed no significant difference in return rates between both groups (P = 0.32). Conclusion: The well-being of FTDs had no influence on their return rate. The intervention of regular contacts during a research project follow-up resulted in an increased return rate of male but not of female FTDs. The pronounced ...