The purpose of this study was to determine the relationship between overweight and dental caries in primary and permanent teeth among Iraqi children aged 7-9 years of both genders in Wassit Governorate . The sample was collected during a period started from 1/ September to 1/November 2010. The weight and height of children were measured using Electronic Body Scale and BMI was calculated to each child in this study. In the present study, it was found that percent of overweight and obesity was 6% and it increased with age. Results showed the mean of DMFT for overweight children was (1.4±1.38) while for normal weight children was (1.29±1.42) and the mean of dmft for overweight children was (4.52 ± 2.51) compared to (4.27 ± 2.56) for normal weight school children. In addition, it was found that prevalence of dental caries in overweight children was 100% and 60% for primary and permanent dentitions, respectively and the prevalence in normal weight was 92.8% and 53.6% for primary and permanent dentitions, respectively. Statistical analysis showed no significant association between overweight and dental caries in primary and permanent teeth. It was concluded that overweight school children had higher mean dental caries scores( DMFT and dmft) and higher prevalence of dental caries in primary and permanent teeth than normal weight school children but there was no significant association between overweight and dental caries prevalence and severity.