Therapeutic decisions made by Emergency Physicians are often influenced by which prescribed medications are being taken by patients. We sought to assess Emergency Department (ED) patients' knowledge of their medications by using a survey. A convenience sample of adult ED patients was surveyed verbally by a research assistant. Two-hundred patients were enrolled. Only 48% of patients could recall or produce a list or the actual bottles of all of their medications, 39% knew the times they take their medications, and only 24% knew all the dosages. Seventeen percent brought a list or the actual medication bottles with them to the ED. Patients who had a primary care physician knew all their medications 51% of the time, compared to 43% who did not have a physician. Fifty-one percent of insured patients compared to 38% of non-insured patients could identify all of their medications. Although knowledge of medications is often critical for decision making in the ED, a significant number of patients are unable to provide this information.