Background and Purpose: Death by whole brain criteria (brain death) is a clinical diagnosis. We sought to identify aspects of brain death that were unclear to both health care personnel and patient families. Methods: Institutional review board approved cross-sectional survey study of attendings, medical trainees (residents and fellows), senior medical students, advanced practice providers (APPs), and critical care nursing (registered nurses [RNs]) at a tertiary referral center over 6 months (March 2018 to September 2018). Surveys were completed on paper or electronically. Participants supplied the top 3 of (1) their own personal questions regarding brain death and (2) questions received from patient families about brain death from a prepared list of questions. Results: Two hundred twenty-nine individuals participated in the survey, with a response rate of 46%. Participation rates in brain death declaration among attendings (92%), RNs (84%), APPs (100%), and trainees of which included fellows (92%) and residents (85%) were high. Most frequently asked questions by trainees and health care personnel were “What are brain death mimics?” and “What is the gold standard testing?”. Questions received from patient families most commonly include “What is brain death?” and “Is brain death reversible?”. All medical students had questions about brain death. Greater than 75% of attendings endorsed having questions regarding brain death. Conclusion: Many health care personnel are involved with brain death declaration, but there are gaps in their understanding about fundamentals regarding brain death. We identify a need for early and targeted brain death education regarding brain death and family communication for various members of the health care profession.