Introduction. Survey data regarding the prevalence of risky substance use in the emergency department (ED) is not consistent. The objective of this study is to identify the prevalence of risky substance use among injured ED patients based on the Alcohol, Smoking and Substance Involvement Screening Test (ASSIST v3.0). A secondary objective was to report on the feasibility of administering the ASSIST to this population, based on the time to conduct screening.  Methods. This cross-sectional study used screening data from a randomized controlled trial.  Injured ED patients completed the ASSIST on a tablet computer, and an ASSIST score was computed that indicated the need for a brief or intensive treatment intervention (risky use) for alcohol and other substances.  For a subsample, data to complete each step of screening was recorded.  Results. Between July 2010 and March 2013, 5,695 patients completed the ASSIST.  Most (92%) reported lifetime use of at least one substance and 51% reported current risky use of at least one substance.  Mean time to complete the ASSIST was 5.4 minutes and screening was feasible even when paused for clinical care to proceed. Conclusion. Estimates of risky substance use based on the ASSIST in our large sample of injured ED patients are higher than previously reported in other studies of ED patients, possibly due to the current focus on an injured population.  In addition, it was feasible to administer the ASSIST to patients in the course of their clinical care.