Background: Informed consent is not always possible in emergency research particularly during life threatening situations. Deferral of consent is an acceptable method in consenting patients; however, it is underutilized. We aim to share our experience with deferred consent. Methods: Participants in two prospective studies underwent a CT-Perfusion scan (intervention) at the time of first hospital imaging, in order not to impact clinical treatment. Deferred consent was then obtained. The primary outcome was the rate of deferred consent. The number of days to obtain consent, refusal rate, and waiver of consent rate was also reported. Results: A total of 291 patients (200 severe traumatic brain injury [TBI] and 91 out-of-hospital cardiac arrest) were enrolled between the two emergency CT-perfusion studies. Some (34/291[11.9%]) could not be reached; waiver of consent was granted by our ethics board. Deferred consent was obtained in 252/291(86.6%). The majority were consented by the partner/spouse (25.2%) and most consents took place within 7-days (76.0%) of enrollment. Five (1.7%) refused consent. Deferred consent rates were higher in the cardiac arrest population (97.8%) compared to the severe TBI population (83.7%). Conclusions: Deferred consent is an acceptable method of obtaining consent in emergency research when the intervention risk is low.