AbstractResearch with nonhuman primates is essential to medical progress and will still be necessary for the foreseeable future. Almost all research scientists agree that animal research is critical to understanding basic biology, discovering new treatments for human (and animal) diseases, and maximizing the safety of new medicines while minimizing their harm to humans. All but two of the Nobel prizes in medicine awarded over the last one hundred years have depended on animal research, and the list of modern medicines, vaccines, and other treatments, as well as basic science discoveries, is so extensive that it could not be adequately covered in even a huge volume. Increases in average life span in the last century are the result of improved public health measures, and many diseases may be related to lifestyle choices. But animal research has contributed to understanding these factors and to the development of vaccines and lifesaving treatments. The philosophical debate regarding the benefits and moral costs of animal research has also filled many volumes by ethicists and philosophers. The major arguments against the use of animals in medical research have been explicitly refuted by a few brave scientists, as well as implicitly by the vast majority of the working biomedical science community.My contribution to this discussion is to provide a personal perspective on my decision if, when, and how to use monkeys in research experiments on Parkinson disease. As a physician researcher, I have been working for many years to understand and cure Parkinson disease.