The present study was undertaken to determine the presence and predictors of the subclinical atherosclerosis in obese children. Fifty obese children [mean age: 11.7 +/- 2.5 y, mean body mass index (BMI): 28.2 +/- 4.0 kg/m(2)] and 50 age- and sex-matched healthy nonobese controls (mean age: 11.4 +/- 3.73 y, mean BMI: 17.6 +/- 3.0 kg/m(2)) were enrolled in the present study. Oral glucose tolerance test was performed to all obese subjects. Common carotid artery intima-media thickness (IMT) was measured by high-resolution B-mode ultrasonography. Carotid artery IMT was significantly increased (0.0476 +/- 0.007 versus 0.033 +/- 0.011 cm; p < 0.001) in the obese group. There were significant relations between carotid artery IMT and insulin sensitivity indexes derived from fasting samples (fasting glucose to insulin ratio (FGIR; p = 0.004, r = -0.404), quantitative insulin-sensitivity check index (QUICK-1; p = 0.002, r = -0.401) and homeostasis model assessment of insulin resistance (HOMA-IR; p = 0.034, r = 0.300) in the obese group. In a multivariate regression model, QUICK-I emerged as independent correlates for mean IMT in obese children with the total variance explained being 20.7% (beta = -0.58, p < 0.001). We concluded that insulin resistance is an independent risk factor for increased carotid artery IMT in obese children.