Internet has become an indispensable source of health-related information. However, several studies have shown there to be a lack of quality control for webpages related to disability. Specifically, available content concerning Down syndrome (DS) and dentistry is limited and of dubious quality. The aim of the present study was to assess the quality of online content in Spanish and Portuguese on dental care for individuals with DS. A simultaneous search in Google and Bing using the terms "Down syndrome" and "odontology/dentist/dental treatment" in Spanish and Portuguese was conducted in seven Ibero-American countries (Argentina, Brazil, Chile, Colombia, Spain, Mexico, and Portugal). The first 100 consecutive pages of results from the three combinations of terms in each of the search engines were accessed and selected by applying conventional exclusion criteria. The selected pages were classified according to their authorship, specificity and dissemination potential. The quality of the online content was assessed using the DISCERN questionnaire and the Questionnaire to Evaluate Health Web Sites According to European Criteria (QEEC). The presence of the Health On Net (HON) and Accredited Medical Website (AMW) seals was also assessed. The mean DISCERN score was 2.51±0.85 and 2.57±0.86 for the Spanish and Portuguese webpages, respectively. The mean readability score was 3.43±1.26 and 3.25±1.08 for the Spanish and Portuguese webpages, respectively. None of the selected webpages presented the HONcode or AMW trust seals. The content available online in Spanish and Portuguese regarding Down syndrome and dentistry is scarce and of highly questionable quality.