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  The 3Rs  

What are the three Rs?


The 3Rs are the guiding principles for ethical practice in animal research. They stand for:

  • Replacement: Replacement involves methods that avoid or replace the use of animal models. It can be further split into:
    • Absolute replacement: which for example includes the use of cell culture, organoids and organs-on-a-chip, as well as computer modeling of novel pharmacological compounds, and
    • Partial replacement: which involves the use of invertebrates, that show a lower level of pain perception such as Drosophila melanogaster - a common fruit fly - or even bacteria.
  • Refinement: Refinement aims to improve animal welfare by reducing or avoiding pain, suffering and distress in animal experiments. This can be achieved by improving animal husbandry in research facilities, or by finding less stressfull procedures.
  • Reduction: Reduction refers to methods that reduce the number of animals used per animal trial. The aim is to minimize the total number of animals while maximizing the gained knowledge per animal used at the same time.

For further details click below:


Russel and Burch

R.L. Burch and W.M.S. Russel1

In 1954 William Russel and Rex Burch, two outstanding british biologists, were instructed by the Universities Federation for Animal Welfare (UFAW) to perform a systematic study about the ethical use of animals in laboratory techniques. After finishing their work, Russel and Burch decided to put more emphasis on this area, which resulted in their opus magnum "The Principles of Humane Experimental Technique"2 in 1959.

There they proposed the three Rs as a mean to achieve an end to animal distress in research and thereby increase humanity of experimental techniques.

Back then scientists were hesitant to apply the principles described in this book, since alternatives to animal studies in research were widely regarded to be in an early phase of their development, and disparities between sciences and humanities were increasing.

Still, over the past few decades there has been an ever-increasing scientific interest in these principles, accompanied by the rise of various modern animal rights movements. This eventually led to the integration of the three Rs into the EU legislative framework in the Directive 2010/63/EU.

"Replacement means the substitution for conscious living higher animals of insentient material. Reduction means reduction in the numbers of animals used to obtain information of a given amount and precision. Refinement means any decrease in the incidence or severity of inhumane procedures applied to those animals which still have to be used."

-Russell and Burch: The Principles of Humane Experimental Technique, 19592


Since then, the three Rs have to be considered before performing animal experiments. Before writing research proposals involving laboratory animals, the following questions have to be answered first:

  • Replacement: Is it possible to obtain the required information without the use of live animals?
  • Reduction: Is it possible to reduce the number of animals while obtaining the same amount of knowledge?
  • Refinement: Is there a way to improve the wellbeing of animals used in experiments, e.g. by reducing distress, pain and suffering?

Motivated by an increasing call for animal welfare in research, scientists from the three Medical Universities of Austria established the RepRefRed Society, an organisation which is now part of the global joint effort to promote the three Rs in biomedical research.

Are you interested in joining us? Click here.


1Canadian Council on Animal Care

2Russell and Burch´s 3Rs Then and Now: The Need for Clarity in Definition and Purpose - Jerrold Tannenbaum, and B Taylor Bennett

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Gesellschaft zur Förderung von Alternativen
Biomodellen (The 3R Society)
Postfach 0014
A-8036 Graz