Neuroscience research in non-human primates (NHPs) has delivered fundamental knowledge about human brain function as well as some valuable therapies that have improved the lives of human patients with a variety of brain disorders. Research using NHPs, although it is facing serious challenges, continues to complement studies in human volunteers and patients, and will continue to be needed as the burdens of mental health problems and neurodegenerative diseases increase. At the same time, research into the 3Rs is helping to ameliorate the harms experienced by NHPs in experimental procedures, allowing the effective combination of optimal welfare conditions for the NHPs and high quality research.