The objective of this study was to determine the prevalence of potentially inappropriate medication (PIMs) use in older emergency department (ED) patients based on the updated 2002 Beers criteria. This was a retrospective analysis of 352 consecutive ED visits by patients aged 65 years and older. The mean number of medications taken was 8.4 per patient. In the study population, 111 (32%; 95% confidence interval [CI], 27-36) of 352 patients were taking at least 1 PIM at ED presentation. Propoxyphene/acetaminophen (24/352, 7%; 95% CI, 4-10), muscle relaxants (14/352, 4%; 95% CI, 2-7), and antihistamines (12/352, 3%; 95% CI, 2-6) were the most common PIMs. Among 101 of 193 patients discharged home from the ED with a new prescription, 13 (13%; 95% CI, 6-19) were also given PIMs. The most common PIMs were propoxyphene/acetaminophen (3/101; 95% CI, 1-8), diazepam (3/101; 95% CI, 1-8), cyclobenzaprine (2/101, 2%; 95% CI, 0-7), and diphenhydramine (2/101, 2%; 95% CI, 0-7). Outpatient PIM use in older ED patients is highly prevalent. Further education is needed regarding prescribing practices in this population group.