Introduction: Childhood obesity is a serious public health problem and epidemiological studies are important to identify predictive factors. It is the aim of this study to analyze birth weight as a predict factor of obesity among preschool children.

Methods: 554 preschool children (4-6years-old) were selected by multistage random sampling from rural areas in Rasht. Data collected from health records of households of health systems and interview with parents. Weight and height of children was measured. We considered children with weight- for- height>/= 85th percentile to be overweight and weight- for- height>/= 95th percentile to be obese. Data Analysis was done with SPSS Software Ver. 16. ِdescriptive statistics and X2 was used.

Results: Overall, 256 children(46.4%) were boys, 37 (6.7%) of children were overweight and 36 (6.5%) of these were obese. At birth, 42(7.2%) of children were low birth weight and 28(5%) of them were high birth weight. There was a positive relation between birth weight and catch –up weigh in other periods of life but There were not any differences between overweigh and obesity rate with low birth weight, appropriate birth weight and high birth weight in children.

Conclusion: It seems that birth weight does not predict obesity in childhood and environmental factors have more power on obesity that must be noticed.