In the light of the International Day of Laboratory Animals, we are pleased to share 36 new Standard Operating Procedures (SOPs) in mouse and rat research. These should serve as a guide to working in a manner that is appropriate for animal welfare. In addition, they promote the standardization of currently applied and generally accepted procedures and thus serve quality assurance. In line with the 3R principles, standard operating procedures were formulated by the working group "SOPs in Animal Experimentation" for the purpose of Refinement. The working group includes animal protection officers from institutions in NRW that conduct animal experiments, various representatives of the district regulatory authorities and representatives of the licensing authority in North Rhine-Westphalia (State Office for Nature, Environmental and Consumer Protection). Further details and the SOPs can be downloaded here.