Ending Monkey Experimentation Is No Monkey Business

Monkeys, as well as baboons, macaques, and marmosets, are used in many areas of medical experiments and regulatory testing; however, biological differences severely limit their relevance to human disease and clinical outcomes, contributing to costly translational failures. In contrast, human-based approaches can better model key features of human biology, avoiding species-specific translational barriers. These methods, developed from human cells, tissues, and data, include organoids, human tissue constructs, and organs-on-chips that can replicate the structural, functional, mechanical, and other biophysical properties specific to humans—in ways that are impossible to do in animal experiments.

Beyond scientific concerns with monkey experimentation, life in captivity and invasive procedures cause these animals to experience pain, traumatic stress, and suffering—making it ethically problematic to use them as tools. Laboratory conditions, including cages, transport, noise, handling, restraints, and experimental procedures contribute to acute and chronic stress. In these settings, monkeys can develop harmful abnormal behaviors that may indicate psychological damage, such as self-injurious behavior, pacing and rocking, and withdrawn and depressive-like states. These stresses adversely affect experimental results, exacerbating the impact of biological species differences and further impacting translation to humans.

Monkey experiments cost more than the lives of innocent animals; they are also financially burdensome. Acquiring and maintaining monkeys for use in experiments is expensive, requiring long-term veterinary care and food costs, elaborate caging, and facility maintenance to span their decades-long lifespans. There are seven federally funded monkey experimentation centers across the United States called the National Primate Research Centers, which receive hundreds of millions in funding from the National Institutes of Health (NIH) every year. The failures of monkey experiments to translate to meaningful clinical advancements make continued investment in them even more costly to society.

Below is a roundup of the Physicians Committee’s work to end monkey experiments in favor of more scientific, ethical, and cost-effective human-based methods.

Phasing Out Federally Funded Monkey Experiments

Each year in the United States, more than 100,000 monkeys are held or used in experiments—many of which are funded by the NIH. The Centers for Disease Control and Prevention (CDC) recently announced its decision to phase out all experiments on monkeys, while the Food and Drug Administration released draft guidance outlining reductions in animal experiments, including those using monkeys. Pushing the NIH to make similar decisions, Physicians Committee experts frequently attend NIH advisory committee meetings, including for the Council of Councils, National Institute of Allergy and Infectious Diseases, and National Institute of Neurological Disorders and Stroke, and submit public comments recommending plans to phase out the National Primate Research Centers and the use of monkeys in medical research, and shift agency resources to human-based methods.

These recommendations are in line with NIH’s groundbreaking initiative to prioritize the development and use of human-based research to improve human health and replace animals.

Preventing Increased Funding From Congress for Monkey Experiments

The Physicians Committee has consistently urged Congress to support a shift away from using monkeys in medical research. Last year, $30 million was proposed to expand infrastructure at the National Primate Research Centers. To oppose this funding, the Physicians Committee led a letter signed by 28 organizations and lobbied lawmakers to direct the NIH to begin phasing out the use of monkeys and redirect funds toward nonanimal research infrastructure.   

Protecting Vulnerable Species From Use in Experiments

Biological resource use is one of the greatest threats facing certain species of monkeys, including the long-tailed macaque—a species that was listed as endangered on the International Union for Conservation of Nature’s Red List of endangered species earlier this year.

The long-tailed macaque has seen significant population decline. Recent reports from breeding facilities in Asia included biologically impossible birth rates, pointing to high numbers of illegally wild-caught animals. Together, this information pushed the Convention on International Trade in Endangered Species of Wildlife Fauna and Flora Secretariat to recommend a ban on all long-tailed macaque trade from Cambodia, as well as increased review of trade from several other countries where the species is found.

The Physicians Committee has been monitoring the discussions surrounding this vulnerable species and signed a petition calling for the United States Fish & Wildlife Service to include the long-tailed macaque as threatened or endangered under the Endangered Species Act.

Calling for the Closure of the Oregon National Primate Research Center

In March 2025, the Physicians Committee began a campaign urging Oregon Health & Science University to close the Oregon National Primate Research Center. The campaign included highlighting the center’s history of Animal Welfare Act violations and continued unethical experiments, and the shifting federal priorities away from animal experimentation. The campaign continued with the Physicians Committee filing an official complaint with the NIH, the United States Department of Agriculture, and directly with Oregon Health & Science University asking for an invasive reproductive experiment on monkeys to be shut down.

More than 10,000 Oregonians joined the Physicians Committee in calling for the center’s closure, including Oregon Governor, Tina Kotek. The Oregon State Legislature answered in the form of a budget note that sets conditions for closing the center. The budget note requires Oregon Health & Science University to submit a report by January 1, 2026, evaluating the financial future of the primate center, including plans for closing the center should it lose more than 25% of its total NIH grant income compared to 2024 levels or receive any state funding.

Stopping Monkey Use in Medical Training

In August, Wake Forest University was scheduled to subject small vervet monkeys—some weighing just two pounds—to invasive medical procedures during a course for healthcare providers, including pediatrics residents. Other pediatrics programs in the country use human-based medical simulators, not animals.

After learning of the planned course through a whistleblower, the Physicians Committee and more than 14,000 supporters wrote to the NIH, which funds Wake Forest’s vervet colony, and the university. In addition to the letter, the Physicians Committee filed a formal animal cruelty complaint to the local sheriff and the North Carolina Attorney General requesting them to investigate. After these interventions, the course was cancelled before it began.

Ending Monkey Experiments in the Netherlands

In October 2025, the Dutch Senate voted to phase out public funding for monkey experiments at the Biomedical Primate Research Centre, the largest primate experimentation facility in Europe, and redirect approximately €12.5 million per year in public funds from monkey experiments to human-based methods. The Physicians Committee supported Dutch partners at the foundation Proefdierij (the Dutch Society for the Replacement of Animal Testing), the Netherlands’ leading organization promoting animal-free science, by submitting a letter to members of the Dutch Senate signed by 127 physician members. The letter urged a positive vote for the measure and outlined the ethical and scientific benefits of replacing monkey experiments with human-based methods.