Objective-This report describes trends in opioid prescribing at emergency department (ED) discharge among adults from 2006-2007 through 2016-2017, by selected patient and hospital characteristics and the type of opioids prescribed. Methods-Data are from the 2006-2017 National Hospital Ambulatory Medical Care Survey. The study population included all ED visits by patients aged 18 and over. The main outcome studied was opioids prescribed at ED discharge, defined using Cerner Multum's third-level therapeutic category codes for narcotic analgesics (Code 60) and narcotic-analgesic combinations (Code 191). Results-The percentage of ED visits by adults with opioids prescribed at discharge increased from 2006-2007 (19.0%) through 2010-2011 (21.5%) and then decreased from 2010-2011 through 2016-2017 (14.6%). The rate of decrease was highest among visits by younger adults aged 18-44 (from 25.5% in 2010-2011 to 15.3% in 2016-2017) and those living in medium or small metropolitan counties (24.3% in 2010-2011 to 14.5% in 2016-2017). The percentage of visits with morphine-equivalent opioids prescribed increased from 2006-2007 (11.3%) through 2010-2011 (12.4%) and decreased from 2010-2011 through 2016-2017 (6.7%). The percentage of visits with stronger than morphine opioids prescribed similarly increased from 2006-2007 (3.8%) through 2010-2011 (5.5%) and decreased to 3.0% in 2016-2017. In contrast, the percentage of visits with weaker than morphine opioids prescribed decreased from 4.0% in 2006-2007 through 3.6% in 2010-2011 and increased to 5.0% in 2016-2017. Among all opioids prescribed at discharge, the percentage with acetaminophen-hydrocodone prescribed decreased from 53.1% in 2012-2013 to 41.5% in 2016-2017, with a corresponding increase for both tramadol and acetaminophen-codeine. Top diagnoses associated with an opioid prescribed at discharge included dental pain, urolithiasis (stones in the kidney, bladder, or urinary tract), fracture injuries, back pain, and extremity pain. For all top diagnoses, the percentage of visits with an opioid prescribed decreased from 2010-2011 through 2016-2017, though the decrease was not statistically significant for urolithiasis.