Characterization of genes associated with adipose tissue is key to understanding the pathogenesis of obesity and developing treatments for this disorder. Differential gene expression in the adipose tissue has been described in adulthood but none studies have been developed on childhood. The purpose of this study was to compare gene expression in omental adipose tissue from obese prepubertal and normal weight children. We selected 5 obese (BMI adjusted for age and sex z score >2) and 6 normal weight children. RNA was extracted from omental adipose tissue biopsies and cRNA was hybridizated on the human genome U133 Plus 2.0 Arrays (Affymetrix). Microarray experiments were performed for each sample, and selected group of gene expression values were confirmed with real-time RT-PCR in 10 obese and 10 normal weigth prepubertal children. 1276 genes were found to be differentially expressed at P<0.05. Of those differential genes, 201 were upregulated (Fc>2) and 42 were downregulated (Fc<-2). Genes involved in metabolic and signalling pathways were altered in childhood obesity.