The setting of appropriate standards of behavior allows a minimum degree of animal protection to be established. As indicated in recital 1 of Directive 2010/63 on the protection of animals used for scientific purposes, differences in national legislation may hinder trade in products and substances in the manufacture of which animal experiments are carried out. The way in which animal welfare is protected depends on the level of knowledge of the animals’ ability to feel and respond to pain, so that, as a result, the standard of animal treatment is constantly improving. With the development of biological and medical sciences, the importance of animals has gradually increased and continues to be high due to the continuous use of living organisms in diverse scientific research. The establishment and development of bioethics has necessitated the creation of legal regulations to protect animals used in research and to guarantee their proper treatment. This paper attempts to describe the current legal standards for the protection of animals used in scientific research and comments on possible changes.