Previous studies using small or restricted samples suggest that vasovagal reactions to blood donation are associated with a decreased likelihood of repeat donation. In the present study, we examined data for all allogeneic whole blood donors (n=89,587) in the American Red Cross Blood Services, Central Ohio Region during an entire year. Results of a one-year follow-up revealed that moderate and severe vasovagal reactions reduced the likelihood of repeat donation by 50% or more. Light vasovagal reactions, which represented 97% of all reactions recorded, significantly reduced return rates by 20% for first-time donors and 33% for experienced donors.