The present study successfully utilizes a new ADME Rat Expression Bioarray, containing 1040 metabolism-and toxicology-linked genes, to monitor gene expression from the livers of rats treated with carbon tetrachloride (CCl 4 ). Histopathological analysis, hierarchical clustering methods, and gene expression profiling are compared between the control and CCl 4 -treated animals. A total of 44 transcripts were found to be altered in response to the hepatotoxin, 19 of which were upregulated and 25 were downregulated. Some of these gene expression changes were expected and concurred with previously published data while others were novel findings.