The Food and Drug Administration (FDA) is announcing the availability of a guidance entitled "M3(R2) Nonclinical Safety Studies for the Conduct of Human Clinical Trials and Marketing Authorization for Pharmaceuticals.'' The guidance was prepared under the auspices of the International Conference on Harmonisation of Technical Requirements for Registration of Pharmaceuticals for Human Use (ICH). The guidance, which is a revision of an existing guidance, discusses the types of nonclinical studies, their scope and duration, and their relation to the conduct of human clinical trials and marketing authorization for pharmaceuticals. The guidance is intended to facilitate the timely conduct of clinical trials and reduce the unnecessary use of animals and other drug development resources.