This case studies report is part of the OECD effort to develop guidance for regulatory applications of (Quantitative) Structure-Activity Relationship [(Q)SAR] models, and emphasizes the use of programme-specific case studies to highlight the importance of legal and practical constraints and information requirements of individual regulatory programmes within OECD member countries in applying (Q)SAR approaches. This report provides a snapshot of the experiences of OECD member countries with respect to the use of (Q)SAR models in chemical assessment. The document provides both current regulatory uses in OECD member countries as well as prospective regulatory applications -- especially those within the European Union (EU) member states as a result of proposed legislation on chemicals (i.e., Registration, Evaluation, Authorisation and Restriction of Chemicals (REACH)). As such, the case studies report should be regarded as a living document which will be updated periodically as requested by member countries to describe the expanding role of (Q)SAR in regulatory settings...