The National Centre for the Replacement, Refinement and Reduction of Animals in Research (NC3Rs) is leading an initiative to improve the design and reporting of animal research. The ARRIVE (Animal Research: Reporting of In Vivo Experiments) guidelines (www.nc3rs.org.uk/ARRIVE) were developed in consultation with scientists, statisticians, journal editors and research funders with the aim to maximise information published and minimise unnecessary animal studies. The guidelines consist of a checklist of 20 items, which researchers can use when designing and reporting scientific experiments to ensure animal studies are robust, transparent and reproducible. Over 600 journals, major research funders, universities and learned societies endorse the guidelines and the recent translation of the guidelines into popular languages, has contributed to their widespread international adoption. Following on from the ARRIVE guidelines, the NC3Rs has developed the Experimental Design Assistant (https://eda.nc3rs.org.uk), an online tool to help guide researchers through the design and analysis of their experiments to improve the robustness and transparency of animal studies and ensure the minimum number of animals is used to reach the scientific objectives of the study.