Background and Aim: Food and nutrition is one of the most essential needs of human societies and gaining sufficient and suitable food for all people is based on food security. Children are one of the most volnurable groups, so researchers and nutritionest emphasize on studying and analyzing of different aspects, effects and associated facters on prevalence of food insecurity and obesity among children. This study aimed to determine the association between obesity and food security and some related family factors inYazd primery school children.

Materials and Methods: Using two stage cluster sampling from 35 Yazd primary schools, a total of 3245 students aged 9-11y (1587 boys & 1658 girls) were randomly selected. Then 187 students 9-11y who had a BMI 95th percentile of Hosseini et al. (1999) reference, were identified as obese and 187 same age and gender pupils (having 15th<85th percentile) were studied as controls. Data were collected by demographic and USDA questionnaires.

Results: We found that the prevalence of obesity among student aged 9-11 years was 13.3% and the prevalence of food insecurity was 30.5%. Data analysing indicated that with adjusting variables such as "paternal education and occupation, economic status" there was a significant association between obesity and food insecurity in these levels: father's educated by secondary school, self-employment and low and moderate level of economic status. However, no significant association was observed between obesity and food insecurity when family size and maternal education were adjusted.

Conclusion: Paternal education and occupation, and family economic status were recognised as associated factors with food insecurity but other factors didn,t show significant relationship. There is lack of published information regarding some factors affecting food security; therefore, it is necessary to performe such studies in other regions too.