OBJECTIVE: To study the correlation between obesity and hypersensitive C-reactive protein (hsCRP), leptin, and insulin sensitive index (ISI) in children. METHODS: The subjects included 69 obese volunteers and 30 age and gender-matched normal volunteers who were recruited from 13 702 children aged 2 to 18 years in Xiangtan City by sampling survey. The body mass index (BMI), hsCRP, leptin, fasting plasma glucose (FPG), and fasting insulin (INS) were tested, and then the ISI was calculated. The results between the obese and normal children were compared. The correlation between the parameters was evaluated. RESULTS: The values of hsCRP, leptin and INS in obese children were significantly higher than those in the normal controls (P<0.01), but the ISI in obese children was significantly lower than that in normal controls (P<0.01).The BMI was significantly positively correlated with the values of hsCRP, leptin and INS (r=0.225, P<0.05; r=0.776, P<0.01; r=0.568, P<0.01), but was significantly negatively correlated with the ISI (r=-0.889, P<0.01). There was a positive correlation between the value of hsCRP and the values of FPG and INS (r=0.429, P<0.01; r=0.206, P<0.05), and there was a negative correlation between the value of hsCRP and the ISI (r=-0.889, P<0.01). The value of leptin significantly positively correlated with the values of INS and BMI, and significantly negatively correlated with the ISI. CONCLUSIONS: Insulin resistance and leptin resistance exist in obese children. The inflammatory factors such as CRP and leptin may be involved in the pathogenesis of obesity.