Knowledge of dental and oral health is a very important in supporting behavior to maintain dental and oral hygiene and health. Deaf children have problems in the hearing process. Hearing limitations in deaf children result in a lack of information obtained, including information on dental and oral health. The results of the preliminary study stated that 70% of the dead students did not know about the knowledge of oral health. The purpose of this study was to describe knowledge of dental and oral health in deaf students at SLB Negeri Purworejo. Method: This type of research is descriptive with cross sectional methods. The sampling method uses a saturated sampling technique. The number of samples used were 40 respondents to deaf students at SLB Negeri Purworejo according to the inclusion and exclusion criteria. The research instrument used a questionnaire on dental and oral health knowledge on deaf students. The results of the questionnaire were processed using cross tabulation to determine the results of descriptive analysis. Results: The level of knowledge of deaf students (71.4%) is in the good category at the age of 16-19 years. The level of dental and oral health knowledge of male students is better than the gender of female students with hearing impairment (64.7%). The level of knowledge based on the last education of parents of deaf students was mostly in the good category at the last high school education (61.1%). Conclusion: The level of knowledge about dental and oral health in deaf students is mostly in good category, namely at the age of 16-19 years, gender in male students, the last education of parents of deaf students is high school.