The US Food and Drug Administration (FDA) is committed to facilitating the development, validation, and regulatory acceptance of new toxicological testing methods. The FDA's mission emphasises protecting public health by using the best science through the most efficient means available. There are multiple new technologies currently under development that promise to result in testing methods that are not only more predictive, but also reduce research-to-market time. Although it is well understood that validation is a prerequisite for regulatory acceptance, until now, there has been no formal mechanism for expert peer review and ultimate acceptance of new, validated methods by the regulatory community. A paradigm has emerged to introduce the regulatory scientists who are ultimately responsible for the pre-market review of applications for product approval to the novel testing methods. Although validation criteria have received international harmonisation, there are several issues that challenge a sponsor who generates data to support the relevance and reliability of a new testing method. The conditions under which data are generated (for example, GLP compliance), data submission criteria for review, and the elements of peer review, need to be standardised to facilitate international harmonisation. A model for regulatory acceptance and implementation of new, validated methods, and issues related to data integrity and international harmonisation, is explored.