Animal models have been used in preclinical research for the last 150 years in pharmacological and toxicological research. Preclinical models were extensively employed in the drug development process in the middle of the twentieth century to confirm the efficacy and safety of medications. According to the literature, over 20 million animal subjects are used annually in biomedical research, primarily in mouse and rat models. However, their translation to humans has raised questions about clinical validity, usefulness, and ethical issues, prompting the scientific community to reconsider the use of animals. In January 2023, changes to the Federal Food, Drug, and Cosmetic Act of 1938 were implemented following the passage of the FDA Modernization Act 2.0, which allows alternatives to animal testing and no longer requires animal studies before human clinical trials. It is critical to establish the safety of any investigational drug before proceeding to human clinical trials. According to the World Medical Association (WMA) Declaration of Helsinki, clinical trials must be carried out using a comprehensive understanding of the scientific literature, which includes sufficient evidence from animal and laboratory experiments. However, alternative methods may also be used to ensure the safety of any medications. This chapter summarizes the current state of animal use in research, as well as alternatives and future directions regarding the use of animal models in research.