Previous studies indicated that differential gene expression between hybrids and their parents is responsible for the heterosis. In this paper, we report genome-wide gene expression analysis in roots of a highly heterotic inter-specific hybrid 3338/2463 and its parental inbreds using Barley GeneChip. A total of 1187 genes displayed difference in gene expressions between hybrid 3338/2463 and its parents, and they can be clustered into eight differential expression patterns. Further analysis revealed that among these 1187 genes, 975genes showed high sequence similarity to the GenBank entries, and represented diverse functional categories, such as metabolism, cell growth and maintenance, signal transduction, response to stress, transcription regulation and others. Fourteen genes were selected for RT-PCR analysis and expression patterns of 9 (64.29%) genes were confirmed. Remarkably, 380 differentially expressed genes could be mapped on the Chinese Spring deletion bins, and with the number of genes in seven homoeologous groups being 158, 148, 121, 140,132, 94 and 127 respectively. It is concluded that a combination of systematic identification of differentially expressed genes with comparative mapping would provide further insight into understanding of molecular basis of heterosis.