During November 2013-March 2014, twice as many all-intent drug overdose deaths were reported in Rhode Island as were reported during the same period in previous years. Most deaths were among injection-drug users, and a large percentage involved fentanyl, a synthetic opioid that is 50-100 times more potent than morphine. Clusters of fentanyl-related deaths have been reported recently in several states. From April 2005 to March 2007, time-limited active surveillance from CDC and the Drug Enforcement Administration identified 1,013 deaths caused by illicit fentanyl use in New Jersey; Maryland; Chicago, Illinois; Detroit, Michigan; and Philadelphia, Pennsylvania. Acetyl fentanyl, an illegally produced fentanyl analog, caused a cluster of overdose deaths in northern Rhode Island in 2013.