Introduction & Objective: DMFT Index is the best epidemiologic caries index in dentistry and can show the state of oral and dental hygiene in one society. By considering this index we can design suitable preventive and treatment program for total population of a society. The aim of this descriptive analytical study was evaluation of DMF6 index in 12 years old children in Hamadan city.

Materials & Methods: Using explorer and mirror under natural light, 4 permanent first molars of 480 twelve years old students were examined from the aspect of decay, missing and filling then DMF6 was accounted for each subject. The statistical analysis was done by SPSS 12 and Pearson, Chi- square test.

Results: The mean of DMF6 was 2.17±1.39. DMF6 in girls (2.22) was more than boys (2.12) but this difference was not statistically significant. 72.9% of girls and 72.5% of boys had carries in their first permanent molars. 1.3% of girls and 2.5% of boys had one missing first molar. The difference between girls and boys in missing and decayed teeth was not statistically significant. 22.5% of girls and 11.7% of boys had filling teeth and only this difference was statistically significant. 26% of population had no sound teeth and only 18.8% of them had 4 sound first permanent molors. 72.7% of population had caries and 1.9% had missing and 17.1% had filled teeth.

Conclusion: Analysis of DMF6 showed that untreated caries is the most important problem in 12 years old children in Hamadan.