March 7, 2026 10 min read Add Us On Google Add SciAm The age of animal experiments may be waning Advances in organ and computer models are raising the prospect that some animal experiments could be eliminated. But there are still huge hurdles to overcome By Diana Kwon & Nature magazine Governments have announced plans to reduce the number of animals, such as mice, used in experimental procedures. Philip Cheung for The Washington Post /Getty Images Last November, the UK government announced a bold plan to phase out animal testing in some areas of research. Animal tests for skin irritation are scheduled for elimination this year, and some studies on dogs should be slashed by 2030. The long-term vision is “a world where the use of animals in science is eliminated in all but exceptional circumstances,” the government policy reads. Other nations are making similar moves. Last April, the US Food and Drug Administration (FDA) announced plans to make animal studies the “exception rather than the norm” in drug safety and toxicity testing in 3–5 years. The same month, the US National Institutes of Health (NIH) revealed an initiative to reduce the use of animals in research that it funds. This year, the European Commission plans to publish a road map to end animal testing in chemical safety assessments. Ethical and animal-welfare concerns have long fuelled efforts to curb animal use in research — and now rapid advances in alternative scientific methods are accelerating the shift. These ‘new approach methodologies’ (NAMs) include devices known as organs-on-chips, 3D tissue cultures called organoids and computational models, such as artificial-intelligence systems. The number of biomedical publications using only NAMs grew from around 25,000 to 100,000 between 2006 and 2022, according to an analysis of studies on seven diseases by Animal Free Research UK, an organization that promotes the replacement of animal experiments. And China is investing heavily in this area: in 2024, it launched the Human Organ Physiopathology Emulation System, an infrastructure project dedicated to developing NAMs, backed with an investment of 2,640 million yuan (US$382 million). On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing . By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. Proponents say that NAMs can be better than animals at mimicking human biology and predicting whether new drugs are safe and effective. Organs-on-chips and organoids are often created with human cells, and computational models can be designed using human data. The shift towards alternative models is “long overdue,” says Donald Ingber, a bioengineer at the Wyss Institute for Biologically Inspired Engineering in Boston, Massachusetts, and a co-founder of Emulate, a biotechnology company in Boston focused on organs-on-chips. But NAMs are a long way from ousting all animal procedures in research, scientists say. Some biological systems are too complex and unpredictable to study without animals. And many of the alternative methods have yet to be validated — to show that they represent the system they are modelling accurately and reproducibly enough to satisfy drug and chemical regulators. “Not all of these [alternative] models are ready for prime time,” Ingber says. On the decline Efforts to replace, reduce and refine the use of animals in research (known as the 3Rs) have been ramping up for decades; in some places, use of animals is already falling. Data from the United Kingdom show that the number of scientific procedures on animals fell from 4.14 million in 2015 to 2.64 million in 2024. The total number of animals used in research and testing in the European Union and Norway dropped by 5% between 2018 and 2022. (The number used in the United States is hard to pin down because the law does not require reporting on rats, mice and fish.) In the United Kingdom, around 76% of experimental animal procedures are for basic and applied research: understanding organisms, modelling disease and developing new therapies. Another 22% are part of regulatory procedures — mostly testing the toxicity and safety of new medicines and other chemicals before they can be used. Some 67% of all procedures involve mice or rats (see go.nature.com/3mzfkgw ). But these and other animals have limitations, especially when it comes to understanding and intervening in human diseases. Medicines that work in animal models during preclinical testing often prove ineffective in humans. This is one major reason that around 86% of investigational drugs fail in clinical trials, and why many researchers are focused on developing alternatives. Take sepsis, for instance, a severe reaction to infection. Researchers have developed more than 100 therapie