||DrugMatrix is the scientific communities' largest molecular toxicology reference database and informatics system. DrugMatrix is populated with the comprehensive results of thousands of highly controlled and standardized toxicological experiments in which rats or primary rat hepatocytes were systematically treated with therapeutic, industrial, and environmental chemicals at both non-toxic and toxic doses. Following administration of these compounds in vivo, comprehensive studies of the effects of these compounds were carried out at multiple time points and in multiple target organs. These studies included extensive pharmacology, clinical chemistry, hematology, histology, body and organ weights, and clinical observations. Additionally, a curation team extracted all relevant information on the compounds from the literature, the Physicians' Desk Reference, package inserts, and other relevant sources. The heart of the DrugMatrix database is large-scale gene expression data generated by extracting RNA from the toxicologically relevant organs and tissues and applying these RNAs to the GE Codelink™ 10,000 gene rat array and more recently the Affymetrix whole genome 230 2.0 rat GeneChip® array.