There are 20 million American adults who cannot read. The demographics of the illiterate population suggest that they represent a significant proportion of patients cared for in a teaching hospital emergency department. This study was designed to assess whether readability of written material given to patients in a university hospital ED matched the literacy level of these patients. Data were gathered from 111 consecutive adult ED patients. Results of the survey showed that although the median education level of ED patients was 10th grade, more than 40% could not be expected to read at the 8th grade level, and at least 20% could be considered functionally illiterate. Readability of ED patient-directed materials was measured using the Fry index. Hospital and commercially generated patients education materials ranged from 8th to 13th grade level; a patient-directed brochure from Virginia ACEP is written at a college reading level. Comprehension of the "leaving against medical advice" (AMA) form or a consent for surgery would require at least an 11th grade education. This study shows that there is an alarming discrepancy between ED patient literacy levels in our sample and the reading skills required to comprehend important written medical and legal information. More than 50% of ED patients in a teaching hospital may read below the level required to understand standard discharge instructions. In addition, understanding the "operative consent" and leaving AMA forms requires a level of education beyond that of the majority of ED patients. If patient-directed written material is to serve its purpose, then ED patient populations should be surveyed and the reading level of written material adjusted accordingly.