As the opioid epidemic in the United States has continued since the early 2000s (1,2), most descriptions have focused on misuse and deaths. Increased cooperation with state and local partners has enabled more rapid and comprehensive surveillance of nonfatal opioid overdoses (3).* Naloxone administrations obtained from emergency medical services (EMS) patient care records have served as a useful proxy for overdose surveillance in individual communities and might be a previously unused data source to describe the opioid epidemic, including fatal and nonfatal events, on a national level (4-6). Using data from the National Emergency Medical Services Information System (NEMSIS),† the trend in rate of EMS naloxone administration events from 2012 to 2016 was compared with opioid overdose mortality rates from National Vital Statistics System multiple cause-of-death mortality files. During 2012-2016, the rate of EMS naloxone administration events increased 75.1%, from 573.6 to 1004.4 administrations per 100,000 EMS events, mirroring the 79.7% increase in opioid overdose mortality from 7.4 deaths per 100,000 persons to 13.3. A bimodal age distribution of patients receiving naloxone from EMS parallels a similar age distribution of deaths, with persons aged 25-34 years and 45-54 years most affected. However, an accurate estimate of the complete injury burden of the opioid epidemic requires assessing nonfatal overdoses in addition to deaths. Evaluating and monitoring nonfatal overdose events via the novel approach of using EMS data might assist in the development of timely interventions to address the evolving opioid crisis.