The facts

01 How many monkeys?

In 2025 there were 2,236 scientific procedures on monkeys in Great Britain, up 15% on 2024. Of those, 2,115 were on cynomolgus (long-tailed) macaques, 71 on marmosets and tamarins and 50 on rhesus macaques.

1,845 individual monkeys were used for the first time in 2025, up from 1,478 the year before.

Numbers had been falling, from 3,246 in 2014 to 1,936 in 2024. Last year that reversed.

02 What are they used for?

88% of procedures on monkeys in 2025 were for regulatory purposes: mostly testing whether new medicines are safe before they're given to people. For cynomolgus macaques, none were classed as basic research.

The Home Office classed 29% of procedures as "moderate" severity and 3 as "severe". A further 24 were non-recovery: the animal was under anaesthetic throughout and was killed without waking.

03 Where do they come from?

In 2025, 95% of the macaques used for the first time were born outside the UK: 1,300 in Africa and 372 in Asia. Only 83 were born here. Mauritius is the biggest exporter of long-tailed macaques from Africa, though the government's figures don't name countries.

47% were the offspring of wild-caught mothers, up from 27% in 2024. Monkeys caught in the wild can't be used in British labs, but their babies can.

The law only requires marmosets to come from captive-bred parents. For macaques, the government accepted in August 2025 that new licences should only use animals from captive-bred parents or self-sustaining colonies. That came with a transition period, and a permanent exemption where a lab can give a scientific justification.

04 The journey here

In November 2024 The Independent reported that macaques from Mauritius and Vietnam were flown to Manchester in journeys of up to 25 hours, in crates too small to stand up in. Photos released under freedom of information showed blood-stained crates.

Campaigners say more than 1,100 macaques were flown into Manchester in 2025. That's a campaign count, not an official figure.

05 An endangered species

The long-tailed macaque, the species Britain uses most, was listed as Endangered by the IUCN in 2022, and the listing was reaffirmed in October 2025. The research industry has challenged it.

Globally, demand is huge. In 2024 there were over 100,000 monkeys in US research facilities. When China stopped exporting monkeys in 2020, prices rose and pressure on other supplying countries grew. In 2022 the US charged Cambodian officials over an alleged scheme to pass off wild-caught macaques as captive-bred. One was acquitted in 2024.

06 Does it even work?

The US Food and Drug Administration says over 90% of drugs that appear safe and effective in animals don't go on to be approved. That's not all down to animal tests, but it shows how often they fail to predict what happens in people.

In 2006, six healthy volunteers at Northwick Park Hospital in London suffered a life-threatening reaction to the drug TGN1412. It had appeared safe in monkeys, and the trial dose was 500 times lower than the highest dose that caused no harm in monkeys.

In April 2025 the FDA announced a plan to phase out its animal testing requirement for monoclonal antibodies, a type of drug that is often tested on monkeys. It aims to make animal studies "the exception rather than the norm".

07 What the UK government has promised

In November 2025 the government published Replacing animals in science, its strategy to phase animal testing down. For monkeys and dogs it set two 2030 targets: at least 35% fewer used in one kind of drug study (pharmacokinetics) and at least 50% fewer in cardiovascular safety studies.

That's progress on paper. But the Home Office says its current statistics can't yet measure either target, and the number of experiments on monkeys went up the same year. Promises need people watching them. That's us.