The first section of this text provides an overview of in vitro toxicology. The molecular biology of cellular toxicity, receptor-mediated mechanisms, structure-activity relationships, pharmacokinetic modelling and the use of biosensors in toxicological studies are treated in detail. The second part of the text covers some of the aspects that allow the analysis of the mechanisms of toxicity: for example, intercellular communication and signal processing, the cytoskeleton, apoptosis and free radical mediated toxicity. The last section presents in vitro studies on hepatotoxicity, dermal toxicity, immunotoxicity, nephrotoxicity and respiratory toxicity.