Objectives: This study evaluated the quality, reliability and readability of information on the Internet on adult orthodontics. Design: A quality assessment of adult orthodontic websites. Setting: Postgraduate Orthodontic Unit, Cork University Dental School and Hospital, Cork, Ireland. Method: An Internet search using three search engines (Google, Yahoo and Bing) was conducted using the terms ('adult orthodontics' and 'adult braces'). The first 50 websites from each engine and under each search term were screened and exclusion criteria applied. Included websites were then assessed for quality using four methods: the HON seal, JAMA benchmarks, the DISCERN instrument and the LIDA tool. Readability of included websites was assessed using the Flesch Reading Ease Score (FRES). Results: Only 13 websites met the inclusion criteria. Most were of US origin (n = 8; 61%). The authors of the websites were dentists (n = 5; 39%), professional organizations (n = 2; 15%), past patients (n = 2; 15%) and unspecified (n = 4; 31%). Only 1 website displayed the HON seal and three websites contained all JAMA benchmarks. The mean overall score for DISCERN was 3.9/5 and the mean total LIDA score was 115/144. The average FRES score was 63.1/100. Conclusions: The number of informative websites on adult orthodontics is low and these are of moderate quality. More accurate, high-quality Internet resources are required on adult orthodontics. Recommendations are made as to how this may be achieved.