PURPOSE: Irritable Bowel Syndrome (IBS) is one of the most common chronic gastrointestinal disorders affecting children, adolescents and adults. Diet plays an important role for management of subjects with IBS. For medical conditions such as this one, the Internet has become one of the primary sources of health information. However, the quality and reading grade level of Internet IBS dietary information is unknown. Our objective was to evaluate both the overall quality and reading level of Internet dietary recommendations for both pediatric and adult IBS. METHODS: Two search engines each identified the top 30 websites for the terms “IBS, diet, children” and “IBS, diet, adults”. Included websites were in English and provided IBS dietary information. Duplicate websites, those which required payment, and those in the format of blogs, magazine articles, or videos were excluded. Health information quality was assessed by three physician raters using the DISCERN instrument. Readability was assessed using the Flesch-Kincaid Grade Level (FKGL) test. RESULTS: Twenty-four pediatric-focused websites and 29 adult-focused websites met criteria for further evaluation. Nine different diets and eleven different diets were recommended by the pediatric-focused and adult-focused websites respectively, being the most frequent High fiber and low FODMAPs diets. With respect to quality, only 4 (17%) and 9 (32%) of pediatric-focused and adult-focused websites were of high quality, respectively. Readability was difficult to read with FKGL grade scores of 11 ± 3.0 and 11.4 ± 5.0 for the pediatric-focused and adult-focused websites respectively. CONCLUSIONS: Internet IBS dietary recommendations for patients vary greatly, are infrequently of high quality, and are often too difficult to read. These results stress the need for Internet-based high quality, easily comprehensible dietary guidelines for children and adults with IBS.