en پژوهشي Original Research Articles <p style="text-align: justify;"><strong>Objectives: </strong>The aim of this study was to determine the prevalence of flat foot in a population of 7-12 year old students and to investigate the relationship between flat foot and age and sex.</p> <p style="text-align: justify;"><strong>Methods:</strong> In this cross-sectional study, a total of 945 students (460 girls and 485 boys) were examined. The presence of flatfoot and the degree of its severity according to Tachdjian&#39;s system of grading for flatfoot was assessed.</p> <p style="text-align: justify;"><strong>Results:</strong> The data showed that the overall prevalence of flat foot was 74% out of which 23% were mild, 34% were moderate and 17% were severe. The prevalence of flat foot in girl and boy students were 75.2% and 72.6% respectively, but this difference was not significant. Moreover, no significant relationship was observed between the prevalence of flat foot and age. <strong>Discussion:</strong> This study showed that flat foot is a common problem among primary school students and should be addressed by responsible organizations.</p> Foot, Flat foot, Prevalence, Students 22 24 http://irj.uswr.ac.ir/browse.php?a_code=A-10-125-2&slc_lang=en&sid=1 Reihaneh Askary Kachoosangy askary_ot@yahoo.com No Tehran University of Medical Sciences, Tehran, Iran. Faranak Aliabadi f-aliabadi@tums.ac.ir Yes Tehran University of Medical Sciences, Tehran, Iran. Mostafa Ghorbani MQORBANI1376@yahoo.com No Alborz University of Medical Sciences, Karaj Iran.