Background and Aim: The aim of the current study was to determine prevalence of obesity and overweight in 2-5 year olds and its association with parental obesity in Birjand. Materials and Methods: This descriptive - analytical study was conducted on five hundred2-5 year olds of Birjand kindergartens and their parents in 2009. Height, weight, and BMI of the subjects were measured using standard methods. In the children, BMI of 85-95 percentile were taken as overweight and BMI≥95 percentile for age and sex were accounted as obese .Regarding parents, BMI of 25 - 29 were considered as overweight and BMI≥30 as obesity. The obtained data was analyzed by means of SPSS software (V: 13) at the significant level of a=0.05.Results: Prevalence of obesity in children was 7.6% (6.3% in girls, 8.8% in boys) and that of overweight was 10.6% (11.7% in girls, 9.6% in boys). Out of all fathers and mothers, 44.2% and 30.2% were overweight, respectively; and also 7.8% of fathers and 6.8 of mothers were obese. Prevalence of overweight and obesity in children of mothers with normal BMI were 15%, but in those having overweight and obese mothers it was 24%. This prevalence was 15.4% in children with normal BMI fathers and in children having overweight and obese fathers it was 20.8%. It was found that there was a significant positive association between children’s BMI and that of their parents (r=0.11, r=0.12, P<0.05).Conclusion: Given the significant and positive correlation between children's and their parents’ obesity, it is important to educate Families to improve their eating patterns and life styles for weight control in their children, particularly in those having obese members.