These are the 3Rs

Two researchers introduced the concept of 3Rs in the 1950s. It is an international shortening that stands for replace, reduce and refine. Everyone who uses animals for scientific purposes within EU shall implement the principles of the 3Rs in their work.

The researchers named William Russell and Rex Burch introduced the concept of 3Rs in an article in 1957. They proposed that researchers should constantly strive to use as few animals as possible and at the same time reduce suffering and improve animal welfare during experiments. The 3Rs for sure contribute to healthy animals and better research.

Today, the 3Rs principles are embodied into both Swedish and European legislation for using animals in research. This means that everyone who uses animals for scientific purposes shall implement the 3Rs in their work.

In a short film, we explain the 3Rs, its impact on research, and the 3Rs Center's role in Sweden.


Replace refers to experiments that can replace live animals with other alternative methods that do not use live animals.

Animal experiments can only be replaced if there are animal free methods that give comparable information to the animal experiment.

Here are some examples of methods that have replaced animal experiments:

  • computer modelling, mathematical modelling and AI
  • artificial organs and tissues, such as organoids and 3D-models
  • organ-on-chip
  • cell cultures or organs ex vivo
  • stem cells
  • research on dead animals that have been euthanized for other purposes than to participate in an experiment
  • research on models instead of real animals
  • research on plants or micro organisms
  • studies on synthetic or electronic material
  • microdosing in humans.


Reduce refers to experiments where the same knowledge and quality of data can be attained buy using fewer research animals than before. It can also mean that you get more information from the same animal than before without increasing the animal's suffering.

These are some examples of how to reduce the number of animals in research:

  • to replace some components of the experimental procedure and thus reducing the number of animals being used even if you cannot replace the entire method or study
  • to share data and results with other researchers, also negative data to reduce experiments
  • to plan and design your experiments to avoid unnecessary use of animals
  • to use organs and tissues from the same animal in several studies or share them with other researchers
  • to use imaging methods to see what is happening inside an animal over time, which can give you more information from the same animal compared to other methods
  • with good animal welfare and the right competence of those who work with the animals, one can reduce the number of animals being used in experiments.


Refine means that you make sure that your laboratory animals experience as little pain, suffering, discomfort and anxiety as possible, compared to previous comparable studies.

Refine also means that you can improve animal welfare and provide your laboratory animals with better life quality, for example by enriched material and larger spaces.

Here are some examples of refinement:

  • to improve and refine pain relief and interventions with the animals
  • to train the animals in approaching people, to be picked up and not to be stressed during various interventions
  • to use materials that help the animals to play, hide and find security or improve the welfare in other ways so that the animals can perform their natural behaviours
  • to make sure that the animals are as short time as possible in experiments and avoid to use the animals’ death as an end point.


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Revision date: 2024-01-02

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