Although commonly acknowledged and applied in clinical research since 2000, preregistration of animal studies is not yet the norm. In 2018 the authors launched the first dedicated, open, online register for animal study protocols: www.preclinicaltrials.eu. In this article, the author provide insight in the development of preclinicaltrials.eu (PCT) and evaluate its use during the first 3 years after its launch. Furthermore, ongoing developments are discussed such as the rise of comparable registries, increasing support for preregistration in the Netherlands and pilots of mandatory preregistration by several funding bodies. The authors also show the international coverage of currently registered protocols but with the overall low number of (pre)registered protocols.