Responding to the imminent threat to public health and safety, the U.S. Drug Enforcement Administration (DEA) has placed U-47700 into Schedule I of the Controlled Substances Act, effective on November 14. Emergency scheduling of dangerous drugs such as U-47700 on a temporary basis is one of the most significant tools DEA can utilize to address the problems associated with deadly new street drugs. U-47700 is a novel synthetic opioid, and its abuse parallels that of heroin, prescription opioids and other novel opioids. Law enforcement agencies report seizures of the drug in powder form and counterfeit tablets that mimic pharmaceutical opioids. Abuse of the drug often happens unknowingly to the user, and it is encountered as a single substance as well as in combination with other drugs such as heroin and fentanyl. DEA received reports of at least 46 confirmed fatalities associated with U-47700, 31 of which occurred in New York and 10 in North Carolina. From October 2015 to September 2016, DEA received 88 reports from state and local forensic laboratories of U-47700 submissions. For information, see https://www.dea.gov/divisions/hq/2016/hq111016.shtml.