3RS principle
The 3R Principle was postulated in 1959 by William Russell and Rex Burch in a book entitled Principles of Humane Experimental Technique. The Principle is today internationally widely recognized by scientists as a moral obligation. It is moreover implemented in many national legislations on animal protection.
Replacement
Methods, which permit a given purpose to be achieved without conducting experiments or other scientific procedures on animals.
Replacement methods can represent full or partial replacement methodologies, based on i) approaches not entailing the use of living animals such as cultured cells (including primary cells), tissues and organs as well as the use of testing strategies that take into account existing in vivo data, in vitro methods, in silico computational methods, physicochemical properties and non-testing data, and/or on ii) use of animals that, based on current scientific evidence, are not considered capable of experiencing suffering such as some invertebrates and immature forms of vertebrates.
Reduction
Reduction methods include careful design and analysis of animal-based experiments so that fewer animals can be used, such as optimization of breeding programmes, experimental designs, statistical analyses, as well as sharing of animals and animal material (organs, tissues, cells), and, if appropriate longitudinal instead of cross-sectional measurements, and measures to reduce unexplained variation in the data.
Refinement
Refinement applies to all aspects of animal care and use, including housing conditions, handling methods, anaesthesia and analgesia, habituation to procedures, execution of procedures, monitoring of health and well-being, humane endpoints, and euthanasia. Refinement also includes the development of better (i.e. more accurate, reliable, sensitive) tools to assess suffering and well-being.
PUBLIC RESOURCES
PUBLIC RESOURCES

3Rs EXPLAINER: Animal use in the development of medicine
The development of new treatments for diseases is difficult – it takes time, collaboration and when there are signs that a certain treatment could be effective, experimentation using animals.

FRONTIERS YOUNG MINDS: Introducing the 3Rs to young minds
Enjoy highlights from an engagement event where students from the International School of Lausanne met scientific authors, educating them about the 3R principle of animal experiments: replacement, reduction, and refinement.

TEACH THE TEACHER: Introduction to the 3Rs and the work of the JRC educational activities
This video is the presentation of the educational activities of the workshop by Marcelle Holloway, JRC (European Commission).
Public Events
Public Events

