The Internet has become an extremely prevalent means of communicating health information to consumers. Guidelines for selecting reliable health information websites give preference to U.S. government sites over commercially funded sites. However, these websites are not useful to consumers unless they are able to read and understand them. The authors' objective was to compare the readability of Internet health information intended for consumers found on U.S. government-funded websites versus that found on commercially funded websites. Consumer health websites were identified through a systematic Internet search. Webpages for 10 common health topics were extracted from each website. Readability of webpages was determined by 3 validated measures: Flesch Reading Ease, Flesch-Kincaid Reading Level, and SMOG Formula. Mean readability of government-funded and commercially funded websites was compared using the Mann-Whitney U test. Commercially funded websites were significantly more difficult to read as measured by Flesch Reading Ease (49.7 vs. 55.6 for government-funded sites, p = .002) and Flesch-Kincaid Reading Level (10.1 vs. 9.3, p = .012). There was no significant difference according to SMOG Formula (12.8 vs. 13.2, p = .150). The overall readability of Internet health information intended for consumers was poor. Efforts should be made to ensure that health information communicated via the Internet is easy for consumers to read and understand.