Interruptions occur frequently in the operating room with both positive and negative consequences. Interruptions can distract anesthesiologists from safety-critical tasks, such as the pretransfusion blood check. In a simulated operating room, 12 anesthesiologists requested blood as part of a "bleeding patient" scenario. They were distracted while their assistant accepted delivery of the product and began transfusing without performing the standard check. Anesthesiologists who immediately engaged with the interruption failed to notice the omission, whereas those who rejected or deferred the interruption all noted and remedied the omitted check (P < 0.05). We discuss the role of displays and strategies on safety.