Objectives: This study was conducted to assess the impact of oral health education program on the level of oral health knowledge among female public intermediate school students in Riyadh. As well as to evaluate the correlation between their oral health knowledge and selected socio-demographic variables. Methods:A pre-posttest quantitative study was conducted at public intermediate girls' schools in Riyadh. A sample of schools was selected using stratified random sampling technique to reflect the spectrum of intermediate schools under the Riyadh's educational regions (north, south, middle, east, and west). Five schools were randomly chosen from the department of education listings in each educational region. A total sample of 315 school students between the ages of 12 and 16 years completed the study. Permission to perform this study was received from the Institutional Review Board of King Saud University and Ministry of Education. A 15-item self-administered questionnaire was designed in Arabic language and used to assess the student's oral health knowledge. Followed by the intervention which consisted of 40 minutes interactive lecture using power point presentation presented by the investigator. The impact of the oral health education program was evaluated by measuring the change in the level of oral health knowledge one month after the program implementation. The data obtained from the questionnaire were entered into a Statistical Package for Social Sciences database (IBM, SPSS version 23, IL, USA). Descriptive statistics were used in calculating the frequency and percentage for categorical sociodemographic characteristics.Mean and standard deviation (SD) were calculated for the continuous variables e.g. age, total score of knowledge. The impact of the program was estimated by calculating the percentage of change in the oral health knowledge which is calculated by 100 (post test score -pretest score)/post test score. McNemar's Chi-square test was used to compare correct / incorrect responses to oral health based questions before and one month after the program implementation. Student t-test and one way analysis of variance (ANOVA) were applied to compare responses to oral health questions in relation to selected socio-demographic variables. A p-value of <0.05 was used to report the statistical significance of results.Results: Three hundred and eighty questionnaires were distributed, out of which three hundred and fifteen were completed giving a response rate of 82.8%. Among the 315 students, 30.8% were first graders, 32.7% second graders, and 36.5% third graders. Nearly 80% of the participants were Saudis and the remaining were non-Saudis. The age range of the participants was 12-16 years with a mean age of 13.98 ± 1.094. Prior to the implementation of the educational program, the question regarding the indication to remove dental plaque and calculus at the dental clinic, received the lowest percentage of correct answers (13.3%). Regarding the knowledge of the number of permanent teeth, only 24.1% of ...