To investigate the factors associated with platelet activation in obese children. Cross-sectional study. Department of Pediatrics of Regional Hospital N∘ 1 of Mexican Institute of Social Security in Morelia, Michoacán, Mexico. 79 obese and 64 non-obese children between the ages of 5 and 10 years. Obese children (body mass index [BMI] >85 in growth curves for Centers for Disease Control/National Center for Health Statistics), and the control group of 64 non-obese children (percentile