This chapter includes information about models for skin absorption testing and skin toxicity testing in a condensed form. At first, the structure and function of human skin is described discussing the contribution of the different skin layers and skin appendages to skin absorption. Moreover, various skin absorption pathways are discussed. Particular attention is paid to the strategies used to test skin invasion. This chapter includes in vivo, ex vivo as well as in vitro experimental setups whose advantages and disadvantages are presented. Finally skin toxicity is addressed paying attention to skin sensitization, skin irritation and corrosion, and skin phototoxicity testing. Altogether an up-to-date status on techniques concerning skin invasion testing and skin toxicity testing is provided.