Toxicogenomics is defined as an integration of genomics (transcriptomics, proteomics and metabolomics) and toxicology. It is a scientific field that studies how the genome is involved in responses to environmental stressors and toxicants. It combines studies of mRNA expression, cell and tissue-wide protein expression and metabonomics to understand the role of gene-environment interactions in disease. One of the important aspects of toxicogenomics research is the development and application of bioinformatics tools and databases in order to facilitate the analysis, mining, visualizing and sharing of the vast amount of biological information being generated in this field. This rapidly growing area promises to have a large impact on many other scientific and medical disciplines as scientists could now generate complete descriptions of how components of biological systems work together in response to various stresses, drugs, or toxicants.