The World Trade Organization (WTO) and the World Organisation for Animal Health (OIE) play an important role in supporting efforts to facilitate the safe trade of animals and animal products by promoting international regulatory cooperation among their Members. International regulatory cooperation is embedded in the Agreement on the Application of Sanitary and Phytosanitary Measures (SPS Agreement) and is an integral part of the work of the Sanitary and Phytosanitary Committee. The OIE plays a crucial part in this cooperation, as the OIE is the WTO reference organisation for international standards related to animal health and zoonoses. The SPS Agreement encourages governments to apply national sanitary measures that are consistent with OIE standards, particularly when making decisions on the importation of animals and animal products. This principle of harmonisation is key to integrating the reference frameworks of the WTO SPS Agreement and the OIE standards. This paper describes international regulatory cooperation, the principle of harmonisation and its expressions, and, finally, the various ways in which the WTO and the OIE cooperate towards the achievement of their goals.