The child overweight is associated with overweight/obesity at the adult age. The obese adipose tissue produces an increase of proinflammatory cytokines as the tumor necrosis factor alpha (TNF-α), causing a deleterious effect on vascular functions. The aim of this work was to evaluate TNF-α levels in a children's population with overweight and its relationship with clinical and laboratory variables. Thirty overweight children were studied, with ages between 8-13 years old, and twenty control children. In both groups waist circumference was measured and body mass index (BMI) calculated. The inclusion criterium was a >85th < 95 th BMI percentile for age and sex. In both groups were determined: fasting blood glucose (glucose-oxidase method); plasma insulin (ECLIA); plasma fibrinogen (Fg, Clauss method); high sensitivity C reactive protein (hsCRP, immunoturbidimetric method); plasma myeloperoxidase (ELISA); TNF-α (ELISA); lipid profile (enzymatic methods); erythrosedimentation rate (ESR) and homeostasis model assessment index (HOMA). Data were expressed as the median and interquartile range. Correlations between variables were investigated with the Spearman's coefficient. A p < 0.05 was considered significant. The TNF-α levels were higher in overweight children [15.4 (13.2-24.0) vs. 12.7 (11.2-14.8) pg/ml; p = 0.028]. Levels of Fg, plasma insulin, HOMA index, uCRP and triglycerides were also statistically significant higher than the control group. The TNF-α was positively correlated with the waist circumference (r = 0.654; p = 0.021). The high TNF-α levels found, with the CRP and Fg levels, confirm a low grade proinflammatory state associated to abdominal obesity in the studied population.