In order to study the relationship between mutation of beta 3-adrenergic-receptor gene and the response to dietary intervention in obese children, 47 obese children were randomly separated into two groups. One was dietary intervention group(36 subjects); the other was control group(11 subjects). The subjects were investigated by dietary survey and anthropometry before and after dietary intervention carried out for 3 months. The mutation of beta 3-adrenergic receptor gene resulting from the replacement of tryptophan by arginine at position 64(Trp64Arg) in encoding amino acid residues was detected by using a polymerase chain reaction-restriction fragment length polymorphisms. The results showed that dietary fat was higher (40.7% of energy from fat) in the obese children. After dietary intervention, the increase of weight(kg) and BMI(kg/m2) were significantly lower in the obese children without mutation than in control group(P < 0.05), but the changes of weight and BMI in the obese children with mutations were similar to those of control group. It was concluded that the Trp64Arg mutation of beta 3-adrenergic receptor gene might be one of the reasons why the effect of dietary intervention was poor in some obese children.