Background: Trauma is the leading cause of death among North Americans between the ages of 1 and 44 years. Resuscitation with hypertonic saline (7.5%) solutions can reduce mortality in hypotensive and brain-injured patients. Study Design: Two multicenter, randomized, clinical trials were designed to compare hypertonic saline resuscitation with or without dextran with conventional isotonic resuscitation in patients with hypovolemic shock or traumatic brain injury. During a 3-year period, 5,848 patients will be randomized, with a primary end point of 28-day survival in the hypovolemic shock cohort and 6-month neurologic outcomes in the traumatic brain injury cohort. Results: This is a report of the study design and implementation of 2 large-scale prehospital intervention trials from the Resuscitation Outcomes Consortium that qualify for exception from informed consent required for emergency research outlined in FDA regulation 21CFR50.24 and the Canadian Tri-Council Agreement for research in emergency health situations (Article 2.8). Conclusions: We have successfully designed and implemented two prehospital intervention trials. The proc-ess has helped define the numerous challenges that must be overcome to pursue exception from informed consent resuscitation research in the prehospital setting. The results of these studies will hopefully advance and improve the early care of the severely injured patient. © 2008 American College of Surgeons.