The Food and Drug Administration (FDA, Agency, or we) is proposing to substitute references to "animal" tests or studies with "nonclinical" tests or studies, add a definition of the terms "nonclinical test" and "nonclinical study," and make other comparable or conforming amendments in certain safety and reporting sections of its regulations. The proposed rule would also substitute "nonclinical" for "preclinical" and "in vitro" for consistency in terminology. These proposed amendments align with recent amendments to the Federal Food, Drug, and Cosmetic Act (FD&C Act) and the Public Health Service Act (PHS Act) and are intended to remove an emphasis, in certain places, on the use of animal testing as the only scientific methodology to assess the safety of a drug in the nonclinical setting. These changes may also foster the development and use of scientifically valid new testing methodologies, potentially improving predictive accuracy of product safety testing while replacing, reducing, or refining animal use. The proposed rule would add no new requirements.