Vasovagal reactions significantly complicate the blood collection process and, more importantly, discourage people who might otherwise donate blood many times from returning. Applied muscle tension is a simple behavioral technique that may reduce vasovagal reactions by maintaining blood pressure. It has been successfully used to treat patients with blood and injury phobias, but has not been applied in the more general, time-limited context of blood collection clinics. Thirty-seven inexperienced blood donors (maximum number of prior donations = 2) attending mobile blood collection clinics were asked to practice applied tension after watching a 2-min instructional video presented on a notebook computer. They were compared with 94 untreated donors with similar donation experience and 47 more experienced blood donors. Treatment reduced the number of symptoms reported on a postdonation questionnaire. It also significantly reduced the amount of medical treatment required (chair reclining) among those who practiced applied tension for the entire period they were in the donation chair.