This two-part study was designed to determine the reading level necessary to understand commonly used emergency department (ED) discharge instructions and the functioning reading level of adult patients treated in an urban hospital ED. In the first phase, 10 preprinted patient discharge instructions were analyzed using the Flesch Reading Ease Score. The average reading level required to comprehend these instructions was 9.8, with a range from the 8th to the 14th grade. In the second phase of the study, a reading exam, based on the Stanford Diagnostic Reading Test, was administered to 82 ED patients prospectively. The mean reading level was 9.8, with a median level of 10; approximately 45% of the ED patients would be unable to understand the preprinted discharge instructions. ED discharge instructions are frequently written at a level beyond the comprehension of a significant portion of the population.