Novice blood donors are at an increased risk for such symptoms as dizziness and lightheadedness. Adverse reactions occur in response to decreases in blood pressure and the resultant inadequate cerebral perfusion. Laboratory studies have demonstrated that water ingestion can produce an acute increase in resting blood pressure. To test this, 83 first-time blood donors (48% female) were randomly assigned to either a pre-donation water or no water condition. Donors in the water condition consumed 500 ml of bottled water approximately 30 minutes before donating. Following donation, all participants completed the Blood Donation Reactions Inventory (BDRI), which is a measure of subjective physiological reactions such as faintness and dizziness. Results of a 2 Group (water, no water) x 2 Sex (male, female) ANOVA of BDRI scores revealed a main effect of Group, F (1, 79) = 11.81, p = .001, reflecting significantly lower BDRI scores in those who consumed water prior to donation.