The data supporting why it is ethical to use animals in scientific research will be reviewed from three perspectives. Historically, important understanding of the mechanisms for diseases such as diabetes and polio and the successful development of effective treatments for them, insulin, and the polio vaccine were made possible only through animal research. More currently, knowledge available 20, 10, and 5 years ago in areas including transplant medicine such as islet cells, hepatitis such as vaccines for hepatitis A and B, and monoclonal antibodies that depend on compassionate animal research will be reviewed. Finally, areas of basic science and treatment that depend importantly on animal research such as stem cells and gene sequencing will be reviewed. The three speakers will highlight how important advances in these areas depend on scientific research that uses animals.