The laboratory rat, Rattus norvegicus, has been used as an animal model in biomedical research for more than 150 years. Rats are used in pharmacological, toxicological, and psychological research due to their genetic similarity to humans, and they have complex behaviours and learning abilities. Rats are similar to humans in many ways, including their nervous system, physiology, and social behaviour, which helps one to understand human diseases and behaviours. The rat has a relatively short lifespan, which allows researchers to conduct long-term studies more effectively, and rat models are also relatively cost-effective. This chapter introduces rats as a species and biomedical model in research and describes the current state and future perspectives of rats as a model for human disease.