Introduction: Long-term outcomes following out-of-hospital cardiac arrest (OHCA) remain poor. Two-thirds of OHCA patients surviving to hospital admission die from neurological injuries, and of those discharged, one-third have irreversible cognitive disabilities due to cerebral ischemia. Near-infrared spectroscopy (NIRS) is a non-invasive imaging technique which is able to continuously detect regional cerebral oxygenation (rSO2). NIRS monitoring has been used to measure rSO2 during in-hospital cardiac arrest resuscitation. Our study is the first feasibility study of paramedics applying NIRS monitoring during OHCA resuscitation. Methods: One NIRS monitor (Equanox 7600; Nonin, Plymouth, MI, USA) was placed on an Emergency Response Unit (ERU) with York Region Paramedic Services. ERU paramedics were trained to apply the device to patients foreheads during OHCA resuscitation and record rSO2 until arrival at hospital or termination of resuscitation. Paramedics did not alter any aspect of patient care by using the NIRS monitor. They were instructed to press an action marker on the device during ACLS interventions (e.g. defibrillation, intubation, medications, etc). rSO2 data was later downloaded for analysis. Our feasibility criteria was to obtain >70% of data files with rSO2 data and >70% of data files with event markers. Results: Data was collected from 24 OHCA patients over a period of 10 months. 19 cases (79%) files contained rSO2 data and 17 cases (71%) had event markers. The rSO2 data present in each file varied widely from complete recording for the entire call duration to sporadic brief readings. Event markers varied from 1 to 10 markers spaced throughout the cases. Conclusion: This is the first study to demonstrate that the use of NIRS by paramedics as part of OHCA resuscitation is feasible. Future studies are required to determine how rSO2 monitoring can be used to guide OHCA resuscitation. The results of this study will help inform protocols for future studies evaluating the use of NIRS in the out-of-hospital setting.