Objectives:The purpose was to evaluate the impact of an oral health promotion program including supervised toothbrushing and educational packages for parents on parent’s knowledge and oral health status of 6- to 7-year-old schoolchildren.Materials and Methods:A multi-stage cluster random sampling method was applied, and schools were allocated to intervention and control groups. After ethical clearance and baseline evaluation, an intervention package consisting of supervised toothbrushing at the school setting, an educational package for parents, and a home package containing toothbrush and fluoridated toothpaste (1000 parts-per-million) were delivered. A post-intervention evaluation was performed after one month on parents’ oral health knowledge and oral hygiene of children using the Oral Hygiene Index Simplified (OHI-S). Schools were considered as a unit of randomization, and a generalized estimating equation (GEE) analysis was performed to apply the cluster effect. Descriptive and analytical analyses were performed using SPSS 22 software.Results:Overall, 701 subjects were re-examined (response rate of 95%). At the one-month follow-up, being in the intervention group (P<0.001, B=−0.028, 95% confidence interval (CI)= −0.33, −0.23) and having higher socioeconomic status [P=0.01, B=−0.12, 95% CI=−0.22, −0.03) were significantly associated with improved oral hygiene status. In the post-test evaluation, parents’ knowledge improvement score regarding oral health in the intervention group was not statistically different from that of the controls (0.51 vs. 0.23). However, the ΔOHI-S improved in the post-test evaluation (−0.27±0.02 vs. 0.02±0.02; P<0.001).Conclusion:Children showed improved oral hygiene status, as measured by the OHI-S, after the program consisting of supervised toothbrushing.