The general population are incidentally exposed to a wide variety of xenobiotics as a consequence of the pollution of the environment by industrial and agricultural chemicals. The action of these xenobiotics on the body shows certain specificity depending upon the compound's chemical structure and reactivity. This text represents the invited contributions from specialists and offers a survey of and insight into the disposition and metabolism of a few environmentally and industrially significant xenobiotics. The topics include: an assessment of drug metabolizing enzymes in the liver; DNA damage by reactive oxygen species gernerated by pesticides; the role of NO in liver injury; hepatotrophic growth factor in liver regeneration; extracellular matrix in the liver oncogene expression in liver injury; hepatocarcinogenesis; and oxidative stress and undifferentiated gene expression. Detailed analysis of the validity of liver function tests have also been included. A chapter addresses the problem of apoptosis, which plays a key role in the signal transduction system of xenobiotics - induced liver injury.