An estimated 100 million animals are used in experiments each year across the world. Using animals in experiments is a controversial issue and it remains the case that there is disagreement over whether experiments on animals are necessary or whether they are alternatives. In the UK, the use of animals in experiments is regulated by the Animals (Scientific Procedures) Act 1986, which is administered by the Home Office. Under this law, all breeding and use of animals has to be carried out in licenced premises, the research itself has to be set out in detail in a project licence which is submitted to the Home Office for authorisation, and the people carrying out the research also have to be licenced.

Experiments on animals are carried out for many different purposes which include developing and testing medicines and vaccines for humans and other animals, studying how animals' and humans' bodies function and assessing the safety of chemicals, such as pesticides or household products, for their possible effects on human health or the environment.

There is concern from welfare organisations that the level of pain and distress experienced by animals during procedures is substantial and there is also cocner over the way animals used for experiments are kept, handled and bred.

It is important that the necessity and justification for using animals is always critically reviewed and that every possible step is taken to reduce the numbers of animals used, and to significantly reduce their suffering and improve their welfare.