We aimed to assess the endothelial function in obese children and adolescents by using a non invasive high resolution ultrasound assessment of the carotid intima media thickness (CIMT). Case control study was conducted on 49 obese children and adolescents comparing them with 24 healthy weight sex and age matched control group in The New Pediatric Hospital, Cairo University. For all subjects, the following were done: full history tacking and clinical examination, anthropometric measurements of obesity in the form weight, height, BMI, skin fold thickness(SFT), waist circumference and hip circumference, laboratory investigations in the form of total cholesterol, triglycerides, HDL, LDL, C-peptide fasting glucose and insulin and ultrasound measurements of CIMT.There were positive significant correlation between the CIMT and the anthropometric measurements including: weight, BMI, BMI SDS, waist circumference, hip circumference, triceps SFT, subscapular SFT and with the supracristal SFT while there was negative correlation between CIMT and the height SDS. There were positive significant correlation between the CIMT and the total cholestrol, triglycerides, LDL and fasting insulin but there were no significant correlation between the CIMT and fasting glucose or C-peptide and there was negative correlation between CIMT and HDL. We concluded that obese children are at increased risk of having thickened CIMT, especially in relation to weight, height, skin fold thickness (SFT), waist circumference, hip circumference, total cholesterol, triglycerides, low-density lipoprotein (LDL) and insulin levels.