To analyze the relationship between oral health knowledge and educational level among an adult population in Spain, and between oral health knowledge and subjects? oral hygiene practices, dietary habits, toxic habits, and oral quality of life. This transversal study used the Comprehensive Measure of Oral Health Knowledge (CMOHK) questionnaire to evaluate subjects? knowledge and understanding of oral health, and the World Health Organization oral health questionnaire for adults to evaluate dietary, oral hygiene, toxic habits, and oral quality of life. Participants (n=400) gave their informed consent and data release permission before taking part in the study, which was approved by the University of Valencia Ethics Committee (certificate No.: H145160675341). Statistical analysis was performed using SPSS v22.0 software, applying Student?s t-test, ANOVA, and chi2 test, with significance set at p<0.05. Oral health knowledge results were: low 41.5% and high 58.5%. An association was found between educational level and oral health knowledge (Chi2: p=0.000). Oral hygiene habits presenting an association with higher levels of oral health knowledge were dental floss use, a higher number of teeth present, and lower prevalence of partial prostheses. A significant association was found between oral quality of life and oral health knowledge. Oral health knowledge is associated with the individual subject?s educational level. But oral health knowledge is not necessarily reflected in the practice of healthy habits.