Nonhuman primates (NHPs), such as chimpanzees, squirrel monkeys, and macaques, are used in research because their genetics, brains, and behavior overlap in many ways with those of humans. These similarities have driven their use across multiple fields, but they also heighten welfare concerns, since primates experience stress, pain, and complex social needs. (Learn more about the use of other animals in science.)
About primate use
Primates are used in many research areas, such as neuroscience, infectious disease, toxicology, and behavioral research. Chimpanzee research has ended in the United States and Europe, but tens of thousands of other primates remain in laboratories and breeding facilities worldwide. In neuroscience, for example, macaques are used in studies of vision, cognition, and motor control. The protocols may involve, for example, restraint chairs or implanted headposts, and animals may be reused across multiple experiments. Infectious disease work has used monkeys to study various diseases, including HIV, malaria, and hepatitis, and sometimes in early-stage vaccine development during public health emergencies. Behavioral and cognitive studies may involve restraint, certain food or water schedules to motivate engaging in tasks, or implanted devices to monitor brain activity. In total, this accounts for large numbers each year—about 65,000 primates in the United States, about 7,000 in the European Union, and additional use in Asia, Africa, and Latin America.
Chimpanzees in research
Chimpanzees once played a central role in research programs in the United States, Europe, and parts of Africa. In the 1950s, when this research began, chimpanzees were taken from Africa for spaceflight programs. Later they were bred in federally supported colonies for HIV/AIDS research though, it became clear that, despite their genetic similarities to humans, they were poor models for AIDS research. As research involving chimpanzees expanded, research programs supported by U.S. and European funders established large chimpanzee colonies in countries such as Liberia, Gabon, and Sierra Leone.
By the early 2000s, however, Europe had prohibited great ape research. In 2015, U.S. agencies, including the NIH and FDA, announced they would no longer support chimpanzee research. Also in 2015, captive chimpanzees were listed as endangered (rather than just wild chimpanzees), extending stronger protections. Many chimpanzees have since been retired to sanctuaries, such as Chimp Haven in Louisiana and Save the Chimps Florida. As of 2025, all but 150 chimpanzees remain in U.S. government or private research facilities, down from a peak number of around 1,500 in the 1990s. Additionally, West African sanctuaries have been saddled with caring for chimpanzees left behind by international research programs and with much more limited resources.
Other nonhuman primates
After chimpanzee use ended in the U.S. and Europe, other species continued to be used. Macaques account for the majority, particularly in drug development and neuroscience. Marmosets are increasingly used in genetics and brain research, in part because they are relatively small and fast-breeding. Baboons and squirrel monkeys are utilized in cardiovascular, transplantation, and behavioral studies.
The supply chain for these NHPs is global. Until 2020, when it banned the export of primates for research, China was the largest supplier. After its ban, other countries like Mauritius, Cambodia, and Vietnam filled the gap by starting large breeding facilities, which export tens of thousands of macaques annually, largely to meet U.S. and European demand.
Laboratory environments often provide limited space, minimal enrichment, and constrained opportunities for exercise and social interaction, with the type of research largely dictating the animals’ particular conditions. For example, primates involved in long-term infectious-disease or neuroscience studies are frequently housed singly. This kind of isolation is associated with extreme stress, indicated by repetitive behaviors like pacing and rocking, as well as self-injury. Even where enrichment and group housing are provided, conditions are far different from natural settings. For example, wild macaques travel long distances daily in complex social groups, whereas in laboratories they have far less space and stimulation. Certain research practices, such as restraint chairs and repeated imaging or surgical sessions, compound the trauma experienced by the animals.
In the United States, primates other than rats, mice, and birds fall under the Animal Welfare Act (AWA), which sets minimum standards for housing, care, and veterinary treatment, though they are often inadequate. Institutions receiving federal funds must also follow the Public Health Service policy, which involves additional standards, and proposed studies are reviewed by Institutional Animal Care and Use Committees (IACUCs). IACUCs are established internally by institutions, so there is no guarantee of objectivity or fairness. Standards are enforced by the USDA Animal and Plant Health Inspection Service (APHIS), which conducts inspections and also requires that facilities submit annual reports for AWA-covered species. These reports can be accessed in the USDA Animal Care Public Search Tool. In the European Union, Directive 2010/63/EU prohibits great ape research and restricts primate use to situations where no alternative exists. In other parts of the world, standards and enforcement vary and are generally weaker.
While the end of chimpanzee research in the United States signaled a significant step forward, large numbers of monkeys and other primates still remain in laboratories and breeding facilities. But advances in non-animal methods, such as organ-on-a-chip systems, human cell models, and advanced imaging and computer models, continue to help shift research away from animal models. Also, in a notable policy change, in 2025 the National Institutes of Health announced that all grant applicants must consider non-animal alternatives.
