BACKGROUND Vocabulary and writing style have been shown to affect the readability of patient-education materials. Readability is generally defined as the ease of understanding or comprehension because of the style of writing. Microsoft Word software (Microsoft Corporation, Bellevue, WA) can quantify and report readability statistics, providing both the Flesch Reading Ease score and the Flesch-Kincaid Grade Level score of selected documents. METHODS This study evaluated the readability of 22 endodontic patient education web sites and 15 endodontic patient education brochures. The web sites and brochures were arbitrarily selected based on availability, reputation of the source, and relevance to endodontic patients. RESULTS The Flesch Reading Ease score and the Flesch-Kincaid Grade Level score were determined for the 37 selected materials. The Flesch Reading Ease scores varied between 44.4 and 76.6, and the Flesch-Kincaid Grade Level scores ranged between 4.5 and 10.6. CONCLUSIONS These findings remind practitioners that some patients may have difficulty reading some endodontic educational materials.