Recent research has extended the role of the neurohormone oxytocin far beyond mating and bonding. Oxytocin now appears as a cornerstone that allows individuals to adapt their group interaction in a flexible, age and context-dependent manner. On the other hand, recent data showed that the cerebellum actually contributes to cognitive, emotional, and perceptual brain functions. Finally, both oxytocin and its receptors are present in the cerebellum, but this system remains poorly characterized.Here, we studied the effects of oxytocin-receptor (OXTR) activation on Purkinje cell activity in vitro and in vivo. Patch-clamp recordings in acute slices showed that OXTR activation reduced spontaneous action potential firing while increasing the dynamical range of the input-output responses. The OXTR agonist TGOT reduced the amplitude of the parallel-fibber to Purkinje cell responses, sometimes after a transient increase. In vivo, microinjections of oxytocin or TGOT reduced Purkinje cell spontaneous firing recorded with multi-electrode arrays. All these effects were inhibited by the OXTR antagonist L-368,899.Together, our data evidence a functional oxytocinergic system in the mouse cerebellum and pave the way for further investigation of the cerebellar oxytocin-system.