We investigated 477 consecutive blood donors in order to find the predictive value of a questionnaire as a screening method for preventing passive transfer of IgE antibodies to common allergens that might cause transfusion reactions. Of the 477 donors, 119 (24.9%) claimed to be allergic and 358 (75.1%) recorded no allergic complaints. Serological examination with Phadiatop® and a multi-allergen mix for food (fx5) detected IgE antibodies in only 54.5% of the allegedly alllergic blood donors. Among the allegedly asymptomatic donors, 12.3% showed positive results in these tests. Subsequently, radioallergosorbent test analyses with common inhalant and food allergens were performed to specify the IgE responses obtained. Our results demonstrate a remarkable difference between the questionnaire answers and the serological measurements of IgE antibodies and raise the question of whether – and if so, what kind of – allergy screening is warranted among presumptive blood donors.