Statements By Scientists

Research with animals has consistently failed to produce effective and reliable results for human biomedical research. This is best illustrated by the number of scientists and clinicians who over the years have acknowledged the shortcomings of animal research, many of whom themselves conduct animal experiments.

This listing is just a sampling of many such statements, and could unfortunately be greatly expanded.


Animal Research - A Timeline for Failure 


“The attrition rate between data developed on animals and the correlation in the clinic is extremely low, and the majority of research projects fail before they ever get tested in humans.”

--Dr. Pascal Descargues, Ph.D., founder of biotechnology company Genoskin

April 27, 2021 

“Time after time it has been proven that animals are an insufficient predictor of drug safety, or efficacy in humans. Consider the statistics. More than 90% of drugs entering clinical trials fail, despite positive results in preclinical animal tests. In part, this is because animals do not have the same immune systems, nor do they contract many of the same diseases humans do, such as major types of heart disease, some cancers, HIV, Parkinson’s, and Schizophrenia.”

--Dr. Pascal Descargues, Ph.D., founder of biotechnology company Genoskin,

April 27, 2021 

"Petri dish and animal models often fail to provide good ways to mimic disease or predict how drugs will work in humans, resulting in much wasted time and money while patients wait for therapies. To address that challenge, NIH, DARPA, and FDA are collaborating to develop 3D platforms engineered to support living human tissues and cells, called tissue chips or organs-on-chips. An integrated body-on-a-chip is the ultimate goal."

NIH-Wide Strategic Plan, page 38, December 16, 2015

1920s - 1950s

“Work on [the polio vaccine] was long delayed by the erroneous conception of the nature of human disease, based on the misleading experimental models of the disease in monkeys.”

 - Dr. Albert Sabin, inventor of the polio vaccine, testifying on April 26, 1984 before the House of Representatives, Subcommittee on Hospitals and Health Care, Committee of Veterans Affairs, serial no. 98-48.


"The methods of assessing toxicity in animals are largely empirical and unvalidated... It is urgently necessary to know whether the tests as in fact conducted have sufficient predictive value to be justifiable, or whether they are a colossal waste of resources to no good purpose."

- Professors Laurence, McLean and Weatherall, writing in the introduction to their book, Safety Testing of New Drugs - Laboratory Predictions and Clinical Performance, ed. DR Laurence, AEM McLean & M Weatherall, publ. Academic Press, 1984.


“Surely not even the most zealous toxicologist would deny that epidemiology, and epidemiology alone, has indicted and incriminated the cigarette as a potent carcinogenic agent, or would claim that experimental animal toxicology could ever have done the job with the same definition.”

- Dr. Michael Utidjian, writing in Perspectives in Basic and Applied Toxicology, p 309-329, ed. Bryan Ballantyne, publ. Butterworth, 1988


“Extrapolating from one species to another is fraught with uncertainty…For almost all of the chemicals tested to date, rodent bioassays have not been cost-effective. They give limited and uncertain information on carcinogenicity, generally give no indication of mechanism of action, and require years to complete. [They are] rarely the best approach for deciding whether to classify a chemical as a human carcinogen.”

- Dr. Lester Lave, of Carnegie Mellon Univ., and Drs. Ennever, Rosenkrantz and Omenn, writing in Nature, Vol 336, p 631, 1988


“The standard carcinogen tests that use rodents are an obsolescent relic of the ignorance of past decades.”

- Philip Abelson, Editor of Science. Science (1990), Sep 21, p 1357.


“Scientists have been modeling ischemic stroke in animals for over 150 years and have devised many ingenious methods to try to mimic the human condition.  … While the use of these experimental models has provided much information about the methods of producing and potentially treating cerebral ischemia and infarction in animal species, the relevance of most of these data to the human condition remains dubious.”

- Wiebers DO, Adams HP Jr, Whisnant JP.  Animal models of stroke: are they relevant to human disease? Stroke. 1990 Jan;21(1):1-3.


“We always have a battle on the issue of what to do with the animal data.”

- Dr. Edward Stein, Health Scientist, US Occupational Safety and Health Administration (Brinkley, 1993).


“So much evidence has accumulated that chemicals frequently have wholly different effects in animals and humans that officials throughout government and industry often do not act on the studies’ findings.”

- Brinkley, Joel, New York Times, “Many say lab-animal tests fail to measure human risk,” March 23, 1993, p A1


"It is impossible to give reliable general rules for the validity of extrapolation from one species to another. [This] can often only be verified after the first trials in the target species [humans]. Extrapolation from animal models. . . will always remain a matter of hindsight."

- Handbook of Laboratory Animal Science , Volume II: Animal Models  Svendensen and Hau (Eds.) CRC Press 1994 p6.


“The history of cancer research has been a history of curing cancer in the mouse … We have cured mice of cancer for decades, and it simply didn’t work in humans.”

- Dr. Richard Klausner, National Cancer Institute, LA Times, May 6, 1998.


 “Animal tests were neither needed, nor used, to explore the ability of the protease inhibitors to block the growth of the AIDS virus. In this case, the target actions was already well-understood and could be evaluated before the clinical trials using computers, cell culture and biochemical assays.”

- Bennett M. Shapiro, Executive Vice President, Worldwide Basic Research, Merck & Co. Inc, NJ, Positive Nation, December 1997/January 1998.


"I can't tell you what it is that those [chimpanzee] studies have given us that has really made a difference in the way we approach people with this disease [HIV/AIDS]."

- Thomas Insel, MD, former director of the Yerkes Regional Primate Center as quoted in  The Scientist 13[16]:7, Aug. 16, 1999.


“There isn’t a single genetically manipulated mouse that has been used yet to produce a drug that cures a disease.”

- Kathleen Murray, director of transgenic services at Charles River Laboratories; The Scientist 16 [3]; 22, Feb. 4, 2002


“As therapies for human diseases become ever more sophisticated and specifically targeted, it becomes increasingly important to understand the potential limitations of extrapolating data from mice to humans. The literature is littered with examples of therapies that work well in mice but fail to provide similar efficacy in humans.”

- Mestas J, Hughes CC. 2004  Of mice and not men: differences between mouse and human immunology. J Immunol. Mar 1;172(5):2731-8.

"The clinical trials of nimodipine and low level laser therapy were conducted concurrently with the animal studies, while the clinical trials of fluid resuscitation, thrombolytic therapy, and endothelin receptor blockade went ahead despite evidence of harm from the animal studies. This suggests that the animal data were regarded as irrelevant, calling into question why the studies were done in the first place and seriously undermining the principle that animal experiments are necessary to inform clinical medicine."

- Pound P, et al. Where is the evidence that animal research benefits humans? BMJ. 2004;328(7438):514–517. 


"The biomedical model is failing …Even if we know all there is to know about the animal model we don't necessarily know about the disease. …The model becomes what we study, not the human disease. …It's a fundamental flaw. We need a fundamentally new approach."

- Susan Fitzpatrick, Ph.D., vice-president of the James S. McDonnell Foundation in Saint Louis, Missouri, as quoted in Philips, H., The Insider - Focus on Neuroscience. Brainstorming. . New Scientist, 2004. 184(2469): p. 54.


“Currently, nine out of ten experimental drugs fail in clinical studies because we cannot accurately predict how they will behave in people based on laboratory and animal studies”

- Mike Leavitt, Secretary of Health and Human Services, U.S. Department of Health and Human Services (Food and Drug Administration press release, FDA Issues Advice to Make Earliest Stages of Clinical Drug Development More Efficient, January 12, 2006)


“Finally, poor replication of even high-quality animal studies should be expected by those who conduct clinical research.”

- Hackam DG, Redelmeier DA. 2006. Translation of research evidence from animals to humans. JAMA. Oct 11;296(14):1731-2.


“Despite decades of research using various animal models for type 1 diabetes, we are still struggling to define the initiating autoantigens, the precise mechanisms of beta cell destruction, and suitable immune-based interventions to prevent or treat human diabetes. ... Although [these] animal models of autoimmune diabetes have proved to be valuable tools to study certain aspects of the disease process, they have also led to misconceptions and erroneous extrapolations, as well as false expectations with regard to the efficacy of immunotherapy. It is therefore time to ask ourselves whether we are making major strategic mistakes when employing rodent models for the study of type 1 diabetes.”

- Roep, BO. Are insights gained from NOD mice sufficient to guide clinical translation? Another inconvenient truth. Ann N Y Acad Sci. 2007 Apr; 1103:1-10.


“Recent advances in systems biology, testing in cells and tissues, and related scientific fields offer the potential to fundamentally change the way chemicals are tested for risks they may pose to humans, says a new report from the National Research Council.  The report outlines a new approach that would rely less heavily on animal studies and instead focus on in vitro methods that evaluate chemicals' effects on biological processes using cells, cell lines, or cellular components, preferably of human origin.  . … Over time, the need for traditional animal testing could be greatly reduced, and possibly even eliminated someday, says the report.” [emphasis added]

- Press release, June 12, 2007. “Report Calls for New Directions, Innovative Approaches in Testing Chemicals for Toxicity to Humans” The National Academies of Sciences report commissioned by the Environmental Protection Agency.


"The reason we use animal tests is because we have a comfort level with the process . . . not because it is the correct process, not because it gives us any real new information we need to make decisions … Animal tests are no longer the gold standard. It is a marvelously new world."

- Melvin E. Andersen, director of the division of computational systems biology at the Hamner Institutes for Health Sciences near Raleigh, N.C.  as quoted in Gaul, GM, In U.S., Few Alternatives To Testing On Animals, Washington Post, April 12, 2008.

"Some animal tests haven't changed in 60 years. The tests are frozen in time. This is not science. Science is always moving ahead."

- Thomas Hartung, Head of The European Center for the Evaluation of Alternative Methods (ECVAM) as quoted in Gaul, GM, Washington Post, April 12, 2008.

“Animals don't reflect the reality of cancer in humans. We cure cancer in animals all the time, but not in people."

- Fran Visco, Founder of the National Breast Cancer Coalition and cancer survivor, as quoted in Begley, Sharon, We fought cancer …. and cancer won.” Newsweek, September 15, 2008.

"Animal models have not been very predictive of how well [cancer] drugs would do in people. We put a human tumor under the mouse's skin, and that microenvironment doesn't reflect a person's—the blood vessels, inflammatory cells or cells of the immune system.”

- Paul Bunn MD, Director, International Society for the Study of Lung Cancer, , as quoted in Begley, Sharon, We fought cancer …. and cancer won.” Newsweek, September 15, 2008.

“This [over reliance on mice] has skewed the field so much that most clinically trained immunologists keep at least a few (and usually a lot more) mice in the “back room” so that they can have a steady flow of papers, grant funding, etc., and some have abandoned human work entirely as a lost cause. But this is just the price of progress, no? Well, except that mice are lousy models for clinical studies. This is readily apparent in autoimmunity and in cancer immunotherapy where of dozens (if not hundreds) of protocols that work well in mice, very few have been successful in humans. Similarly, in neurological diseases, the mouse models have also been disappointing.”

- Davis, MM, Director Stanford University Institute for Immunity, Transplantation and Infection. “A prescription for human immunology.” Immunity. 2008 Dec 19;29(6):835-8.


“These [non-animal] models have the ability to be far more accurate. I sometimes think it is just tradition — that feeling that if it’s safe in an animal it’s safe in a human — which means so many animal tests are still carried out.”

- Kelly BéruBé, cell biologist, Cardiff University, as quoted in The Times Online (UK), June 5, 2009, accessed at


"Ultimately, what this means is that many preliminary tests on animal cells -- particularly in medically relevant projects -- may not only be useless, but the findings from this kind of early testing may even be misleading," … "Our latest study demonstrates that animal model systems are inadequate for a great many tests of this kind," Particularly when we're talking about developing safe and effective stem cell therapies, we will still need human ES cells as the gold standard against which to compare everything else. In such cases, lengthy preliminary testing on animal cells risks wasting valuable time and resources."

- Dr. Hans Schöler from the Max Planck Institute for Molecular Biomedicine, as quoted in ScienceDaily, 9 March 2010. Max-Planck-Gesellschaft. "Deceptive model: Stem cells of humans and mice differ more strongly than suspected."


"The use of animal models for therapeutic development and target validation is time consuming, costly, and may not accurately predict efficacy in humans. As a result, many clinical compounds are carried forward only to fail in phase II or III trials; many others are probably abandoned because of the shortcomings of the model. Building on a potentially extensive network of collaborations with academic centers and advocacy groups, NCATS [National Center for Advancing Translational Science] will aim to develop more reliable efficacy models that are based on access to biobanks of human tissues, use of human embryonic stem cell and induced pluripotent stem cell models of disease, and improved validation of assays. With earlier and more rigorous target validation in human tissues, it may be justifiable to skip the animal model assessment of efficacy altogether."

- Collins, Francis S., Director, National Institutes of Health, “Reengineering Translational Science: The Time Is Right,” 6 July 2011, Vol. 3, Issue 90, page 1.


“To date, almost all of these [toxicity] studies have been performed on animals. Until more research is done on women, we can’t rule out an environmental link. This is something we’re investigating now at the Dr. Susan Love Research Foundation, including ways to set up virtual human models to study the effect of potential carcinogens in the milk duct. That’s the kind of research that will help clarify this complex issue.”

- Susan Love, MD, founder and president of the Dr. Susan Love Research Foundation and clinical professor of surgery UCLA School of Medicine, speaking about the impact of environmental toxins on breast cancer: Quoted in Better Homes and Gardens, October 2012


"Murine [mouse] models have been extensively used in recent decades to identify and test drug candidates for subsequent human trials. However, few of these human trials have shown success. The success rate is even worse for those trials in the field of inflammation, a condition present in many human diseases. To date, there have been nearly 150 clinical trials testing candidate agents intended to block the inflammatory response in critically ill patients, and every one of these trials failed. … The prevailing assumption—that molecular results from current mouse models developed to mimic human diseases translate directly to human conditions—is challenged by our study. …  our study supports higher priority to focus on the more complex human conditions rather than relying on mouse models to study human inflammatory diseases."

- Seok J, et al. 2013 Genomic responses in mouse models poorly mimic human inflammatory diseases. Proc Natl Acad Sci U S A. 2013 Feb 26;110(9):3507-12.

“We have moved away from studying human disease in humans. We all drank the Kool-Aid on that one, me included. With the ability to knock in or knock out any gene in a mouse—which can’t sue us, researchers have over-relied on animal data. …The problem is that it hasn’t worked, and it’s time we stopped dancing around the problem…We need to refocus and adapt new methodologies for use in humans to understand disease biology in humans.”

- Dr. Elias Zerhouni, Former NIH director, 2002 – 2008, speaking before the NIH Scientific Review Management Board on June 4, 2013 as reported in NIH Record,