This study aimed to evaluate the oral hygiene status of primary school after using a new tooth brushing education program. The 176 subjects were primary school, aged 11-12. Purposive sampling was used for school selection and simple random sampling was used for dividing children into 3 groups; experimental group (57) and 2 control groups, one belonged to the same school (58) as the experimental group and the other belonged to a different school (61). Data collection before implementation was done by using a questionnaire about socio-economic status and tooth brushing behavior, and oral hygiene status was measured by using Stallard et al. plaque index. One month after implementation, oral hygiene status was measured again. Implementation in the experimental group was to teach school teachers how to brush their teeth, and how to teach tooth brushing, effectively. All three groups received tooth brushing sets for the children. The results showed that baseline oral hygiene status was not significantly different between the experimental group and the same school control group, but a significant association was found between these two groups and the different school control groups, in the following areas buccal side of upper right first molar, labial side of upper right central incisor and lower left central incisor. After implementation, oral hygiene status of the experimental group was significantly improved nearly all surfaces, except buccal side of upper left first molar. The same school control group significantly improved on some surfaces; buccal side of upper right first molar, labial side of upper right central incisor and lower left central incisor. The different school control group had a higher score than baseline on lingual side of lower left and right first molar and labial side of lower left central incisor. Among the 3 groups, oral hygiene of the experimental group and the same school control group was significantly better than the different school control group. When compare in the same school, the oral hygiene of experimental group was significantly better than the control group on labial side of lower left central incisor. Therefore; the oral hygiene status of primary school children was improved by this education technique, however, the environment had the effect to change the oral hygiene of children.