To determine whether emergency department patients want to share their medical records across health systems through Health Information Exchange and if so, whether they prefer to sign consent or share their records automatically, 982 adult patients presenting to an emergency department participated in a questionnaire-based interview. The majority (N = 906; 92.3%) were willing to share their data in a Health Information Exchange. Half (N = 490; 49.9%) reported routinely getting healthcare outside the system and 78.6 percent reported having records in other systems. Of those who were willing to share their data in a Health Information Exchange, 54.3 percent wanted to sign consent but 90 percent of those would waive consent in the case of an emergency. Privacy and security were primary concerns of patients not willing to participate in Health Information Exchange and preferring to sign consent. Improved privacy and security protections could increase participation, and findings support consideration of “break-the-glass” provider access to Health Information Exchange records in an emergent situation.