Mankind has been using animals already for a long time for food, for transport and as companion. The use of animals in experimental research parallels the development of medicine, which had its roots in ancient Greece (Aristotle, Hippocrate). With the Cartesian philosophy in the 17th century, experiments on animals could be performed without great moral problems. The discovery of anaesthetics and Darwin's publication on the Origin of Species, defending the biological similarities between man and animal, contributed to the increase of animal experimentation. The increasing demand for high standard animal models together with a critical view on the use of animals led to the development of Laboratory Animal Science in the 1950s with Russell and Burch's three R's of Replacement, Reduction and Refinement as guiding principles, a field that can be defined as a multidisciplinary branch of science, contributing to the quality of animal experiments and to the welfare of laboratory animals. The increased interest in and concern about animal welfare issues led to legislative regulations in many countries and the establishment of animal ethics committees.