With a view to assisting the evaluation of integrated approaches to testing and assessment (IATA) in regulatory decision-making within OECD Member Countries, this guidance document provides guidance on the reporting of defined approaches to testing and assessment in the area of skin sensitisation using the adverse outcome pathway (AOP) as a conceptual framework. Annex 1 (page 25) outlines twelve illustrative case studies for skin sensitisation and Annex 2 (page 279) lists information sources used within the case studies.