Purpose: To evaluate the quality of patient-oriented online information about dental caries using existing consumer evaluation tools and to judge the efficacy of these tools in quality assessment. Materials and Methods: The websites for the evaluation were pooled by using two general search engines (Google and Yahoo!). The search terms were: 'dental caries', 'tooth decay' and 'tooth cavity'. Three assessment tools (LIDA, DISCERN and FRES) were used to evaluate the quality of the information in the areas of accessibility, usability, reliability and readability. Results: In total, 77 websites were analysed. The median scores of LIDA accessibility and usability were 45.0 and 8.0, respectively, which corresponded to a medium level of quality. The median reliability scores for LIDA (12.0) and DISCERN (20.0) both corresponded to low level of quality. The readability was high with the median FRES score 59.7. Conclusion: The websites on caries had good accessibility, usability and readability, while reliability of the information was poor. The LIDA instrument was found to be more convenient than DISCERN and can be recommended to lay people for quick quality assessment. Palabras clave: dental caries, internet, quality of information