This paper reviews the most significant ethical and moral concepts surrounding the use of non-human living beings in scientific experimentation.The principle: “Animals as living beings are capable of suffering and that human beings should respect them and afford them due protection and care” is embodied in Directive 86/609/EEC and the relevant Polish legislation. The essence of Directive 86/609/EEC is exemplified by two rules: (1) animals may only be used when the results of the research will provide additional knowledge or be generally advantageous to humans or animals; (2) man has a moral duty to respect all animals and should bear this in mind to avoid any unnecessary suffering. Experiments on animals should therefore be carried out only when absolutely necessary, and in compliance with national regulations laid down in response tothe Directive. One of the overriding conditions in the use of animals for scientific purposes is adherence to the 3R rule devised by Russel and Burch [1959], i.e. consideration of the possibility of replacing in vivo method with in vitro technique (replacement), reduction in the number of animals to the necessary minimum (reduction), and refinement of experimental methods to limit invasiveness (refinement). The classification of individual procedures used in animal experimentation is discussed, and the numbers of animals used in scientific experiments and teaching in Germany and Poland are presented.