BACKGROUND: A sudden cardiac arrest (SCA) occurs when the heart abruptly stops beating; because of the nature of SCA, capturing data in the out-of-hospital setting from actual bystander response is difficult. Current technologies such as virtual reality (VR) allow the creation of scenarios programmed for heightened realism. No studies have used an immersive VR system to observe lay bystander response. OBJECTIVE: We sought to characterize lay bystander response to an unannounced simulated VR SCA event during a multisensory scenario. METHODS: Using a VR wearable device combined with a cardiopulmonary resuscitation (CPR) recording manikin, we created a 3-minute multisensory SCA scenario that allowed for the observation of lay bystander response. Subjects were unaware of the nature of the emergency event but were told to respond how they would to an emergency situation. Subject's ability to proceed through the American Heart Association's Chain of Survival and their CPR quality were recorded. Frequencies and percentages were calculated using descriptive statistics. RESULTS: Between June 2016 and June 2017, 119 lay subjects were enrolled. Of those, 92% asked for 911 to be called, 81% attempted CPR, 13% requested an automated external defibrillator (AED), and 6% used the AED; 82% stated that they felt as if they were at a real SCA event. Cardiopulmonary resuscitation data were collected (n = 81), the mean CC rate was 93.5 ± 22.4 cpm, and the mean CC depth was 38.4 ± 13.8 mm. CONCLUSIONS: In our unannounced, immersive VR SCA observational study of lay bystanders, most subjects attempted CPR, although the majority did not use an AED.