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Questions and Answers About Monkeys used in Research

The Humane Society of the United States

Q: What types of monkeys are most frequently used in research?
An analysis of federal research grants¹ for 2000 through mid-2002, conducted by The Humane Society of the United States, revealed that macaques (primarily the rhesus macaque) are the most commonly used monkeys; this category also includes crab-eating macaques, pig-tailed macaques and others. Additional species used are marmosets, squirrel monkeys and tamarins.

Q: How many monkeys are used in research in the United States?
A: According to statistics provided by the U.S. Department of Agriculture, 69,990 monkeys were used in research in the US during 2007; an increase of 11 percent since 2006 and the highest number of monkeys used since the USDA started tracking statistics in 1973. Furthermore, this number represents only those monkeys used for research and does not include monkeys used for breeding purposes or those simply being held for research. If one uses the most recent information available, the total number of monkeys in laboratories in the United States, including those used for breeding or being held, is approximately 112,000.

Q: What types of experiments are conducted using monkeys?
A: Monkeys are used extensively in various areas of research including, but not limited to, human pathologies and diseases (such as AIDS, Parkinson's disease and hepatitis), psychological disorders (such as depression and anxiety), toxicology, transplantation, nutrition (including infant nutrition), dentistry, biological warfare and bio-defense, drug abuse, vaccine and other drug testing, and cloning. During infectious disease research, monkeys are infected and the resulting disease is allowed to progress, which can result in symptoms such as severe diarrhea, dehydration, wasting and anorexia, In some cases, the primates receive no intervention and ultimately die from the disease being studied.

Monkeys are also subjected to a wide array of invasive procedures, some of which cause severe pain and distress. These procedures include restraining a monkey for long periods of time (as long as several days), multiple surgeries, food and water deprivation, lethal dosing, irradiation, blood and tissue sampling, and much more. Some procedures involve handling by humans in which leather gloves are used to wrestle the animals out of their cages

Overall, the majority of research conducted on monkeys is harmful². For example, an analysis of monkey research revealed that 77 percent of the grant projects for the years 2000-mid 2002 were harmful, 12 percent were minimally harmful, 8 percent were not harmful, and 3 percent could not be categorized.

Q: How are monkeys housed in research laboratories?
A: Monkeys are social animals and whether or not they are housed with other animals is crucial to their well-being. Animal Welfare Act standards require "provisions to address the social needs of nonhuman primates of species known to exist in social groups in nature" (section 3.81 (a)). Macaques, chimpanzees, marmosets, and almost all other species of primates used in research live in social groups in the wild. The committee at each institution that oversees animal research (known as the Institutional Animal Care and Use Committee) can provide an exemption for "scientific reasons"—but The HSUS believes that such exemptions are often used without adequate justification.

Due to the type of research being conducted—particularly infectious disease research—monkeys used in active protocols are often housed in isolation (single housing). Baker (2007) conducted a survey of 22 primate institutions housing approximately 36,000 primates and compared social housing of all monkeys with those used in research protocols. It was found that while 73 percent of the monkeys were socially housed, only 46 percent of those used for research purposes were. Single housing has been shown to lead to depression, withdrawal, frustration, self-biting, hair pulling, rocking and other psychotic behaviors (Bayne et al, 1992; Bayne et al, 1995; Bellanca, R & Crockett, C, 2002; Jorgensen et al, 1996; Lutz et al, 2003; National Research Council, 1998; Rommeck et al, 2009). Infant monkeys are used in invasive research just as adults are.

Stainless steel cages built for individual monkeys are similar across laboratories. All cages are built with three major considerations in mind: ease of cleaning, access to the monkey, and the ability to fit more animals into a room. The typical cage is enclosed on three sides and the top, bottom and front are made of bars. Monkeys in individual cages have been known to reach out and hold the hand of a neighbor; this may be the only contact that a monkey will have with another. Some monkeys are aggressive to neighbors and reaching around may result in bitten fingers.

Q: What is being done about the psychological well-being of monkeys used in research?
A: It has been 23 years since Congress mandated that psychological well-being of nonhuman primates be addressed. The USDA has continually failed to meet this mandate, essentially leaving laboratories, and other entities to self-regulate. The agency did adopt standards in 1991, but five years later the USDA itself determined that these standards needed to be clarified and made enforceable, which led to the issuance of a draft USDA policy in 1999. While the draft policy would have led to improvements, those regulated under the AWA (including the biomedical industry) managed to stop the regulatory process. As a result, there have been no regulatory changes and the legal standards regarding psychological well-being remain weak and difficult to enforce.

In her recent study, Baker (2007) found that changes to enrichment programs were most often prompted by regulatory or accreditation visits. This supports the argument that improved regulations and their enforcement will improve conditions for primates in laboratories, as Congress intended with passage of the 1985 AWA amendments. Clear standards that can be properly enforced will prompt these facilities to provide their primates with improved care or they could face financial consequences. Is there strong government support for research on monkeys? Recent analyses by The HSUS have shown that the federal government spends over a billion dollars per year on monkey research. The eight National Primate Research Centers alone received $1.2 billion in 2007. The centers were established by Congress in 1960 to provide an infrastructure and resources to investigators conducting primate research. Supported by the National Institute of Health, the centers, according to their annual reports, have more than 27,500 monkeys of 20 different species. There are currently eight National Primate Research Centers:

  • California (Davis, Calif.)
  • New England (Southborough, Mass.)
  •  Oregon (Beaverton, Ore.)
  • Southwest (San Antonio, Texas)
  • Tulane (Covington, La.)
  • Washington (Seattle, Wash.)
  • Wisconsin (Madison, Wis.)
  • Yerkes (Atlanta, Ga.)

Q: Are monkeys imported to the United States to be used in research?
We have seen a vast increase in the number of monkeys imported from other countries to facilities in the United States. In 2006, 26,638 monkeys were imported into the US; a 44% increase over 2004 (IPPL, 2007). Three companies were responsible for over 75% of all of these imports: Covance (11,738), Charles River Laboratories, Inc (5,359) and Shin Nippon Biomedical laboratories (SNBL) (3097); all serve as contract testing laboratories. Some companies own, at least in part, facilities in the originating countries as well. These facilities often capture monkeys from the wild and breed them. Cynomolgus macaques made up 92 percent of the primates imported in 2006, followed by rhesus macaques, marmosets, squirrel monkeys, other macaques, and other primates. Half of the imported primates were from China.

Q: What is the value of using monkeys in biomedical research and testing?
A: The value of research on monkeys has been called into question, particularly as the European Union is considering an end to the use of wild-caught monkeys and chimpanzees. One current debate is in regards to the use of chimpanzees and monkeys for HIV research. It has been widely accepted by the scientific community that using chimpanzees for HIV research was a failure because chimpanzees infected with HIV do not progress to AIDS (Bailey, 2008; Nath, Schumann and Boyer, 2000, and others). A former director of Yerkes National Primate Research Center, Thomas Insel, noted in 1999 that 15 years of HIV research on chimpanzees produced little data relevant to humans, adding "I can't tell you what it is that those studies have given us that has really made a difference in the way we approach people with this disease" (Smaglik, 1999).

As scientists steered away from using chimpanzee for HIV research, attention turned to the use of monkeys, such as rhesus, pigtail and cynomolgus macaque . After years of pursuit and tens of millions of dollars, the failures of the use of monkeys in HIV research are becoming increasingly evident, with AIDS patient advocacy groups calling for an end to funding for this type of research and increased funding for prevention and other avenues (Quinn, 2008). As Bailey noted in his review of HIV vaccine research, over 85 vaccines have gone to human clinical trials and all have failed, with some actually causing increased likelihood of HIV infection.


Bailey, J. (2008) An assessment of the role of chimpanzees in AIDS vaccine research. Alternatives to Laboratory Animals, 36(4):

Baker, K. (2007) Enrichment and primate centers: closing the gap between research and practice. Journal of Applied Animal Welfare Science, 10(1): 49-54.

Bayne K, Dexter S, Suomi S. (1992) A preliminary survey of the incidence of abnormal behavior in rhesus monkeys (Macaca mulatta) relative to housing condition. Lab Anim 21:38–46.

Bayne K, Haines M, Dexter S, Woodman D, Evans C. (1995) Nonhuman primate wounding prevalence: a retrospective analysis. Lab Anim 24:40–44.

Bellanca R, Crockett C. 2002. Factors predicting increased incidence of abnormal behavior in male pigtailed macaques. Am J Primatol 58:57–69.

International Primate Protection League (2007, April) U.S. primate imports spike. Retrieved December 9, 2008 from http://www.ippl.org/2007-us-primate-imports.php

Jorgensen, M.J., Novak, M.A., Kinsey, J., Tiefenbacher, S. & Meyer, J.S. (1996) Correlates of self-injurious behavior in monkeys. XVIth Congress of the International Primatological Society/XIXth Conference of the American Society of Primatologists, Abstract No. 767.

Lutz, C., Well, A. and Novak, M. (2003) Stereotypic and Self-Injurious Behavior in Rhesus Macaques: A Survey and Retrospective Analysis of Environment and Early Experience. American J Primatol 60:1-15 .

Nath, B.E., Schumann, K.E., and Boyer, J.D. (2000) The chimpanzee and other non-human primate models in HIV-1 vaccine research. Trends in Microbiology, 8 (9): 426-431.

National Research Council (1998) The Psychological Well-Being of Nonhuman Primates. Washington: National Academy Press. Quinn, A (2008, March 25) Government sees overhaul of AIDS vaccine effort. National Post, Retrieved December 31, 2008 from http://www.nationalpost.com/life/health/story.html?id=25cf4ab5-b4f1-4dea-9c38-65054b88a180&k=80580

Rommeck, I., Anderson, K., Heagerty, A., Cameron, A., McCowan, B. (2009) Risk factors and remediation of self-injurious and self-abuse behavior in rhesus macaques. J Appl Amin Welf Sci 12(1):61-72.

Smaglik, P. (1999, August 16) AIDS vaccine researchers turn from chimps to monkeys. The Scientist, 13(16). Retrieved December 29, 2008 from http://www.lclark.edu/org/ncal/objects/AIDvaccine.htm

¹ The HSUS retrieved this information from the National Institutes of Health (NIH) Office of Extramural Research's Computer Retrieval of Information on Scientific Projects (CRISP).

² The following practices would be considered as invasive: inoculation with an infectious agent, surgery or biopsy conducted for the sake of research and not for the sake of the nonhuman primate (NHP), and/or drug testing. "Minimally invasive refers to a minor procedure, such as venipuncture,. Finally, "noninvasive" indicates that the animal received no physical or psychological insult.

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